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THE  UNIVERSITY  OF  CHICAGO 
SCIENCE  SERIES 


Editorial  Committee 

ELIAKIM  HASTINGS  MOORE,  Chairman 

JOHN  MERLE  COULTER 

PRESTON  KYES 


THE  UNIVERSITY  OF  CHICAGO 
SCIENCE  SERIES,  established  by  the 
Trustees  of  the  University,  owes  its  origin  to 
a  belief  that  there  should  be  a  medium  of  publica- 
tion occupying  a  position  between  the  technical 
journals  with  their  short  articles  and  the  elaborate 
treatises  which  attempt  to  cover  several  or  all 
aspects  of  a  wide  field.  The  volumes  of  the  series 
will  differ  from  the  discussions  generally  appearing 
in  technical  journals  in  that  they  will  present  the 
complete  results  of  an  experiment  or  series  of 
investigations  which  previously  have  appeared 
only  in  scattered  articles,  if  published  at  all.  On 
the  other  hand,  they  will  differ  from  detailed 
treadses  by  confining  themselves  to  specific  prob- 
lems of  current  interest,  and  in  presenting  the 
subject  in  as  summary  a  manner  and  with  as  little 
technical  detail  as  is  consistent  with  sound  method. 
They  will  be  written  not  only  for  the  specialist 
but  for  the  educated  layman. 


THE  STORY  OF  THE 
MAIZE  PLANT 


,-*!^' 


THE  UNIVERSITY  OF  CHICAGO  PRESS 
CHICAGO,  ILLINOIS 


THE  BAKER  AND  TAYLOR  COMPANY 


THE  CAMBRIDGE  UNIVERSITY  PRESS 


THE  MARUZEN-KABUSHIKI-KAISHA 

TOKYO,  OSAKA,  KYOTO,  FCRUOHA,  SBNDAI 


BOOK  COMPANY 

SHANSHAl 


PLATE  I 


COLORS  OF  THE  ENDOSPERM  OF  MAIZE 

For  explanation  of  plate  see  p.  162 


THE  STORY  OF  THE 
MAIZE  PLANT 


By 

Paul  Weatherwax 

Associate  Professor  of  Botany 
Indiana  University 


THE  UNIVERSITY  OF  CHICAGO  PRESS 
CHICAGO,  ILLINOIS 


Copyright  1923  By 
The  University  of  Chicago 


All  Rights  Reserved 
Published  March  1923 


Composed  and  Printed  By 

The  University  of  Chicago  Press 

Chicago.  Illinois,  U.S.A. 


PREFACE 

Numerous  inquiries  for  specific  information  about 
the  maize  plant  have  come  to  the  writer  in  the  course  of 
the  past  five  or  six  years,  during  which  a  series  of  investi- 
gations on  its  botanical  nature  have  been  in  progress; 
and  it  is  in  an  attempt  to  meet,  in  a  measure,  an  apparent 
need  that  the  following  pages  have  been  prepared. 

The  reliable  literature  on  maize  is  voluminous,  but 
it  is  so  widely  scattered  in  textbooks  and  periodicals, 
and  so  intermingled  with  the  unreliable,  that  it  is  often 
a  hopeless  task  for  the  technical  worker  in  other  fields, 
or  for  the  casual  reader,  to  bring  a  particular  unit  of  the 
material  together  and  to  separate  the  grain  from  the 
chaff  for  any  definite  purpose. 

A  dozen  or  more  monographs  of  the  species  have 
appeared  in  different  countries  in  the  past  century,  but 
they  do  not  answer  satisfactorily  today  the  questions 
that  the  reading  public  is  asking.  Some  have  not  yet 
been  released  from  the  foreign  languages  in  which  they 
were  written,  and  are  often  couched  in  terms  of  the 
prejudiced  or  distorted  point  of  view  of  the  investigator 
where  maize  is  known  only  as  an  exotic  curiosity ;  others 
are  out  of  step  with  modern  scientific  tendencies;  and 
still  others,  the  majority  of  the  list,  in  fact,  are  so  domi- 
nated by  economic  interest  that  their  theme  is  man 
rather  than  maize. 

No  claim  is  made  for  completeness  or  perfectly 
rounded  proportion  in  this  treatment.  These  are  but 
relative  terms  anyhow,  and  judgment  must  be  individual. 


viii  PREFACE 

If  this  work  is  as  poorly  proportioned  in  some  respects 
as  its  predecessors  have  been  in  others,  the  writer  can 
but  hope  that  its  idiosyncrasies  will  make  it  interesting 
to  a  class  of  readers  by  giving  emphasis  to  aspects  less 
adequately  treated  elsewhere. 

With  few  exceptions,  the  illustrations  have  been 
prepared  by  the  writer,  and  many  of  them  especially 
for  this  work.  In  so  far  as  has  been  possible,  the  draw- 
ings have  been  made  directly  from  the  material  or  from 
photographs.  A  consistent  effort  has  been  made  to 
correct  in  these  figures  some  of  the  gross  errors  that 
prevail  in  textbooks  where  maize  is  used  for  illustration. 

Free  use  has  been  made  of  material  previously 
published  by  the  writer  in  short  papers.  Any  difference 
in  opinion  or  in  statement  of  fact  noted  here  may  be 
interpreted  as  corrections  of  errors  that  have  been  dis- 
covered in  the  earlier  articles  subsequent  to  their  publi- 
cation. 

As  indicated  in  the  notes  and  references,  many 
sources  of  information  have  been  drawn  upon  in  an 
attempt  to  get  at  the  truth.  This  has  been  greatly 
facilitated  by  the  kindness  of  many  other  investigators, 
in  this  and  in  other  countries,  who  have  sent  material, 
notes,  and  literature.  In  several  instances,  advantage 
has  been  taken  of  unpublished  criticism  by  other  workers; 
and  throughout  the  preparation  of  this  work  and  the 
researches  that  preceded  it,  Professor  D.  M.  Mottier 
has  given  encouragement,  criticism,  and  suggestions  of 
inestimable  value.  Responsibility  for  the  final  form, 
however,  and  for  views  taken  on  points  in  controversy, 
rests  wholly  with  the  author. 


CONTENTS 

PAGE 

List  of  Illustrations ix 

CHAPTER 

I.  Introduction i 

II.  Names  and  Relationships 4 

Common  names;  technical  names;  classification 

III.  History  and  Geographical  Distribution     .     .        1 1 

Visit  of  the  Northmen;  discovery  by  Columbus; 
introduction  into  Europe;  present  distribution; 
place  of  origin 

IV.  Botanical  Origin 22 

Sources  of  information;  theories  as  to  evolution; 
the  prototype  of  maize  and  its  relatives 

V.  Structure  and  Gerivonation  OF  THE  Seed     .  32 

Partsof  the  seed;  viability;  steps  in  germination 
VI.  Anatomy  and  Physiology  of  the  Stem     ...       39 
Development  of  the  plant;  the  unit  of  structure; 
minute  anatomy;    vascular  bundle;    develop- 
ment of  the  stem 
VII.  Structure  and  Functions  of  the  Leaf    ...       47 
Parts;  phylogenetic  significance;  the  leaf  blade; 
lobed  leaves;  the  epidermis;  color;  histology; 
the  ligule;   metabolism  in  the  leaf;    transpira- 
tion; guttation 

VIII.  Branches  of  the  Shoot 56 

Method  of  branching;  the  pistillate  branch; 
suckers;  the  prophyllum 

IX.  The  Root  System 60 

Tissues  of  the  root ;  root  hairs;  osmosis  and  root 
pressure;  secretion  and  excretion;  prop,  or 
brace  roots 


:  CONTEXT? 

CHAPTER  PACE 

X.  Ecological  Relations 66 

Man  and  the  enWronment  of  the  plant ;  distribu- 
tion; climate;  pollination;  weeds;  birds  and 
small  animals;  insects;  fungous  diseases; 
remedies 

XL  Seed  axd  Pl.\xtixg 8i 

Maize  and  other  cereals;  Com  Belt  methods;  the 
seedbed;  selection  and  care  of  seed;  viability 
and  testing;  grading  of  seed;  hand  planting; 
com  planters;  checkrowing;  inter\-als  of 
planting;  listing 

Xn.  Tillage 88 

Aims;  conserx-ation  of  moisture;  other  aims; 
implements;  processes 

XIII.   H.AR\-ESTIXG 93 

Pasturing;  husking  in  the  field;  cutting;  bind- 
ing; the  com  shredder;  fodder-pulling;  top- 
ping; ensilage 

XI\'.  The  Intlorescexce 99 

Monoecism;  staminate  inflorescence;  pistillate 
inflorescence;  sexual  anomalies;  branched 
ears;    inflorescence  of  suckers;    origin  of  the 

ear 

X\'.  Spikelets  AND  Flo\\-ers 114 

The  grass  spikelet ;  staminate  spikelet  of  maize ; 
pistUlate  spikelet;  sexual  anomalies;  com- 
poimd  spikeletes;  two-flowered  pistillate 
spikelets;  development  of  the  spikelets;  the 
style  and  stigma ;  the  ovule;  tricarpellate  nature 
of  the  ovar}' 

X\T.  Pollination 127 

Agencies;  duration;  optimum  conditions; 
anthesis;  receptivity  of  the  silk;  abundance 
of  pollen;  dichogamy 


CONTEXTS  xi 

CHAPTER  PAGE 

XML    G.\METOGEKESIS  AXD  FeCTXDATIOX 132 

Pollination  and  fecundation;  the  pollen  grain; 
the  poUen  tube;  the  megaspore;  the  embn-o 
sac;  development  of  the  pistU;  fecundation; 
significance  of  double  fecundation 

XMII.  The  Frot 140 

Definition;  structure  of  the  ear;  number  of  rows ; 
size  and  shape  of  the  ear ;  show  com ;  pod  com ; 
the  car>-opsi5 

XIX.  The  Embryo 147 

Early  development;  differentiation;  pseudo- 
polyembryony;  leaves  of  the  embrj-o 

XX.  The  Seed  Coat 150 

Development  of  the  pericarp;  layers  of  the  peri- 
carp; color;  color  of  the  cob 

XXI.  The  Endosperm 153 

Economic  importance;  theoretical  significance; 
early  development;  nuclear  di\'isions;  the 
aleurone  la\-er;  aleurone  pigments;  chemical 
and  physical  nature  of  the  endosperm;  the 
yeUow  pigment;  endosperm  varieties;  "pop- 
ping" of  com 

XXII.  Physical  Character  of  the  C.ajiyopsis    .     .  164 

Size;  shape;  color 

XXIII.  Heredity 169 

Modem  genetics;  maize  in  genetics;  xenia; 
multiple  factors;  h3-brid\-igor;  non-Mendelian 
\iews;  genetics  of  the  future 

XXIV.  Breeding iSi 

A  favorable  field;  antiquity  of  maize  breeding; 
methods;  selection;  hybridization;  technique 
of  hybridization;  pedigree  breeding;  co- 
operative breeding 


xii  CONTENTS 

CHAPTER  P*«^ 

XXV.  Products  and  Uses iS6 

Place  in  human  life;  food  for  live  stock;  milling; 
lye  hominy;  manufactured  products ;  corn  oil; 
starch;  sugar;  syrup;  varieties  used  in  manu- 
facture; sweet  corn;  pop  corn;  cane  sugar; 
fermented  products;  fuel;  the  stem;  the  cobs; 
the  husks;  medicinal  value;  undeveloped 
possibilities 

XXVL   Maize  in  Aboriginal  America i97 

Food  supply  and  civilization;  maize  areas  in 
America;  origin  of  maize  culture;  evolution  of 
maize  culture;  varieties  grown  by  the  Indians; 
agricultural  engineering;  harvesting  and  stor- 
age; uses;  maize  and  religion;  America's 
gift  to  mankind 

XXVII.  Maize  IN  American  Life 217 

The  key  to  early  colonization  in  temperate 
America;  a  staple  commodity  during  industrial 
development  and  territorial  expansion;  Corn 
Belt  prosperity;  socializing  influences;  orna- 
mental properties;  an  inspiration  for  works  of 
art  and  literature 

Bibliography 2^" 


Index 


237 


LIST  OF  ILLUSTRATIONS 

■E 

Colors  of  the  Endosperm  of  Maize   .     frontispiece  facing 


PAGE 


FIG. 

1.  Inflorescence  of  Coix  lachryma-J obi 8 

2.  Tripsacum  dactyl  aides g 

3.  Inflorescence  of  Tripsacum 9 

4.  Spikelets  of  Tripsacum 9 

5.  Pistillate  Spike  of  Euchlaena 9 

6,7.  Staminate  Panicle  and  Spikelets  of  Euchlaena       .      .  10 

8.  Distribution  of  Maize  in  Aboriginal  America      ...  13 

9-13.  Present  Distribution  of  Maize 14-17 

14.  The  First  Published  Figure  of  Maize 18 

15.  A  Hybrid  between  JMaize  and  Teosinte 25 

16-18.  Pistillate    Spikes    of    a    First-Generation    Hybrid 

between  Maize  and  Teosinte 26 

19.  Longitudinal  Section  of  a  Grain  of  Dent  Corn     .      ■      ■  33 

20-23.  Steps  in  the  Germination  of  a  Grain  of  Corn.      .      .  35 

24,  25.  Effects  of  Deep  and  Shallow  Planting      ....  36 

26.  Seedling  near  the  End  of  Germination 37 

27.  The  Cotyledon  at  Work 37 

28.  Cross-Section  of  an  Internode  of  the  Stem    ....  41 
29-32.  Vascular  Bundles  in  Cross-Section      ....       42-44 

33.  Diagram  of  Longitudinal  Section  of  a  Young  Plant, 

Showing  Regions  of  Development 45 

34.  Parts  of  the  Leaf 47 

35.  Parts  of  the  Leaf  of  Arundinaria 47 

36.  Epidermis  of  the  Leaf 49 

37.  Diagram  of  Cross-Section  of  the  Leaf 50 

38,39.  Cross-Sections  of  the  Leaf 50,51 

40, 41.  Mechanism  of  "Rolling"  of  the  Leaf 52 

42-44.  Types  of  Ear-bearing  Branch 56 

45.  Diagram  of  Longitudinal  Section  of  the  Ear-bearing 

Branch 57 

46.  Many-eared  Plant  of  One  of  the  "  Prolific  "  Varieties    .  58 

47.  Plant  with  Basal  Branches 58 

xiii 


xiv  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

48, 49.  Longitudinal  Sections  of  the  Root  Tip    ....  60 

50.  Diagram  of  Cross-Section  of  a  Root 61 

51.  Portions  of  a  Cross-Section  of  a  Young  Root     ...  62 

52.  Portions  of  a  Cross-Section  of  an  Old  Root  ....  62 

53.  A  Root  Hair 63 

54.  Buttress  Roots 64 

55.  Field  of  Corn  Damaged  by  Grasshoppers      ....  74 
56-59.  Corn  Smut 78,  79 

60.  A  Good  Field  of  Com 82 

61.  Corn  in  the  Shock 95 

62.  Stacks  of  "  Pulled  "  Fodder 97 

63.  Degeneracy  Resulting  from  Inbreeding 99 

64, 65.  Dwarf  Corn 100 

66-71.  Some  Types  of  Tassel loi 

72.  Fruiting  Tassel  of  Pod  Corn 102 

73-75.  Staminate  Spikelets 103 

76,  77.  Arrangement  of  Pistillate  Spikelets 104 

78.  Ear  with  Staminate  Tip 105 

7.9-81.  Types  of  Abnormality  in  the  Ear 106 

82.  Ear  with  Branches  at  the  Base 107 

83.  Type  of  Conical  Ear 108 

84.  Ear  of  Branch  Corn 108 

85.  An  Androgynous  Ear 108 

86-91.  Tassel  and  Staminate  Spikelets  of  Branch  Corn  .      .  109 

92-94.  Inflorescences  of  Suckers 109 

95.  A  Pair  of  Staminate  Spikelets 115 

96.  Transverse  Section  of  a  Staminate  Spikelet  .      .      .      .  116 

97.  Longitudinal  Section  of  a  Staminate  Spikelet     .      .      .  ii; 

98.  Longitudinal  Section  of  a  Pistillate  Spikelet .            .  ii^i 

99.  Longitudinal    Section    of    a    Two-flowered    PistUlate 

Spikelet liS 

100.  Ear  of  Country  Gentleman  Sweet  Corn  with  Xenia 

Grains 119 

101-7.  Development  of  the  Spikelet 120 

108,109.  Cross-Sections  of  a  Mature  Anther 122 

1 10-14.  The  Style  and  Stigma 124 

115, 116.  The  Effect  of  Incomplete  Pollination     .      .      .      .  127 

117-22.  Gametes  and  Fecundation 137 


LIST  OF  ILLUSTRATIONS  XV 

FIG.  PAGE 

123-27.  Ears  of  the  Endosperm  Varieties 142 

128-34.  Some  Types  of  Ear 143 

135.  A  Prize-winning  Exhibit  of  Dent  Corn 144 

136-45.  The  Embryo 148 

146-63.  Sections  of  the  Grains  of  the  Principal  Endosperm 

Varieties 160 

164-72.  Some  Types  of  Grain 167 

173.  A  Hill  of  Com 205 

174.  A  Corn  Palace 221 

PLATE 

II.  Pigmentation  of  the  Caryopsis facing  162 


CHAPTER  I 
INTRODUCTION 

It  was  deep  in  the  mists  of  the  past,  long  before  the 
advent  of  the  human  race,  that  Nature  inaugurated 
among  her  gramineous  plants  and  their  environment 
the  set  of  principles  eventually  to  give  rise  to  the  cereals, 
those  large-seeded  grasses  which  provide  today  the  chief 
source  of  food  for  man  and  his  domestic  animals.  After 
one  plan  or  another  she  devised  for  oriental  lands  their 
rice  and  their  millets,  for  Africa  and  parts  of  Asia  the 
sorghum  family,  and  for  the  Semite  in  his  desert  garden 
and  the  Aryan  on  his  westward  migrations,  the  small 
grains  of  Europe  and  Asia.  For  the  vast  wilderness  of 
the  Western  Hemisphere,  however,  she  had  only  a  single 
corn  plant;  but  she  put  into  its  creation  the  best  of  all 
that  had  been  given  to  the  cereals  of  the  Old  World; 
and,  somewhere  in  the  hills  or  plateaus  of  the  American 
tropics,  there  came  into  existence  that  economically 
indispensable  and  botanically  unique  species  that  we 
call  maize  or  Indian  corn. 

For  untold  seasons,  the  plant  grew  and  extended  its 
domain,  the  savage  primate  doubtless  coming,  mean- 
while, with  the  other  animals,  to  eat  its  stems  and  fruits. 
As  man  returned  year  after  year,  and  animal  competition 
made  the  limited  habitat  of  the  plant  an  uncomfortable 
place,  he  began  to  carry  away  choice  morsels  to  eat  in 
a  more  quiet  spot.  But  he  was  still  far  from  the  practice 
of  maize  cultivation.  Year  after  year  he  saw  young 
shoots  appear  above  the  ground,  grow  to  flower  and  fruit, 

FMOFEfirr  LiBRARY 
N.  C.  State  College 


2  THE  STORY  OF  THE  MAIZE  PLANT 

and  die;  and,  in  his  primitive  way,  he  must  have  won- 
dered at  it  all.  It  may  have  been  a  fallen  ear  bearing  a 
tuft  of  seedlings,  or  a  germinating  seed  at  the  entrance 
of  his  den,  that  first  told  the  savage  that  one  of  the  gods 
back  of  the  phenomenon  was  the  fruit  that  he  was 
accustomed  to  pick  from  the  mature  plant;  and,  later, 
he  probably  noticed  that  young  plants  appeared  regularly 
in  new  places  where  seeds  had  been  dropped  accidentally. 
As  soon  as  he  learned  to  bury  a  few  seeds  where  he 
wished  new  plants  to  be,  progress  became  more  rapid; 
and  knowledge  as  to  the  season  and  methods  of  preparing 
the  soil,  planting,  and  cultivation  made  its  own  slow  way 
in  due  time.  Much  later  he  learned  to  use  as  seed  the 
best  of  the  grain  produced,  and  with  this  the  agricultural 
evolution  of  the  species  had  begun. 

When  the  closing  events  of  the  fifteenth  century 
opened  the  wonders  of  a  new  world  to  the  old,  the  explorer 
looked  with  hardly  more  wonder  upon  the  native 
American  himself  than  upon  his  extensive  fields  of  this 
uniquely  useful  plant.  The  maize  plant  was  the  eco- 
nomic stepping-stone  of  the  colonist  in  temperate  North 
America,  and  the  banner  of  the  immigrant  as  he  made 
his  way  into  the  Mississippi  Valley;  and  today  the 
Corn  Belt  is  the  land  of  rationalism,  prosperity,  and 
happiness — the  social  and  economic  bulwark  of  the 
nation.  In  other  countries  where  it  has  been  introduced, 
this  corn  plant  has  immediately  become  popular  in  one 
way  or  another,  but  it  grows  best  and  is  still  most 
appreciated  in  its  native  land. 

A  large  part  of  our  knowledge  of  the  maize  plant 
has  been  derived  from  studies  directed  from  the  preju- 
diced point  of  view  of  the  utihtarian.     These  studies 


INTRODUCTION  3 

have  concerned  themselves  with  methods  of  manipula- 
tion, environmental  relations,  rating  and  improvement 
of  varieties,  feeding  values,  and  distribution  and  utiliza- 
tion. The  aim  of  work  of  this  kind  has  been  to  make  the 
plant  serve  in  a  better  way  the  needs  of  man;  and  the 
organization  of  facts  and  theories  bearing  in  this  direction 
is  now  far  in  advance  of  their  apphcation. 

But  the  biological  individuality  of  the  plant  has  been 
the  guiding  inspiration  of  other  studies.  Here  we 
attempt  to  eliminate  the  influence  of  man's  point  of 
view  and  get  at  that  of  the  plant.  We  are  interested 
in  the  plant  as  a  plant,  with  a  beautifully  characteristic 
structure,  problems  of  its  own  to  solve,  a  life  of  its  own  to 
live,  and  a  part  of  its  own  to  play  in  the  drama  or  organic 
existence. 


CHAPTER  II 

NAIMES  AND  RELATIONSHIPS 

When  the  explorer  makes  his  way  into  an  unknown 
Land,  each  prominent  species  of  plant  or  animal  is 
subject  to  at  least  three  processes  of  nomenclature 
before  it  is  fully  catalogued  as  an  acquisition  of  civiliza- 
tion. One  popular  name  will  be  based  upon  the  native 
appellation,  if  one  exists;  another  will  consist  of  a 
modification  of  the  term  applied  to  the  new  organism's 
nearest  relative  in  the  language  of  the  explorer;  and  to 
these  must  be  added  in  time  the  binomial  designation  of 
science.  The  great  American  cereal  has  met  with  these 
three  tendencies,  and  each  has  given  it  a  permanent  name. 

Common  names. — On  discovering  this  plant  in  the 
West  Indies,  Columbus  adopted  as  its  name  the  word 
mayz,  a  derivative  of  the  native  name  in  many  dialects; 
and  from  this  has  come  our  modern  word  maize.  But 
the  Anglo-Saxon's  first  extended  acquaintance  with  the 
plant  was  made  not  so  much  through  exploration  in 
America  as  in  the  fields  and  gardens  of  Europe,  where 
it  had  been  introduced;  and,  in  the  absence  of  the  direct 
influence  of  the  native  name,  its  derivatives  were  accorded 
less  favor  than  they  deserved.  The  name  maize  remains 
today  the  simplest,  most  expressive,  and  most  definite 
common  name  of  the  species ;  and  it  is  unfortunate  that 
it  has  not  attained  a  more  general  use,  especially  in  the 
United  States. 

For  centuries  the  English-speaking  peoples  have 
applied  to  all  the  cereals  the  class  name  corn,  the  term 


NAMES  AND  RELATIONSHIPS  5 

often  being  used  specifically  for  the  commonest  grain 
crop  in  any  definite  locality.  On  the  introduction  of 
maize,  the  use  of  the  existing  term  was  extended,  and 
the  new  cereal  came  to  be  known  as  Indian  corn  in  many 
countries  of  Europe;  but  to  a  hundred  million  Americans 
today,  maize  is  merely  corn. 

Many  other  common  names  have  been  used  in  limited 
localities  at  dift'erent  times.  These  usually  treat  the 
plant  as  a  kind  of  corn  or  wheat,  the  qualifying  prefix 
often  indicating  the  route  of  introduction  into  that  par- 
ticular locality.  Thus  we  find  such  names  as  Turkish  corn, 
Turkish  wheat,  Indian  wheat,  Roman  corn,  Sicilian  corn, 
and  Indian  millet.  In  South  Africa,  where  the  plant  has 
recently  assumed  great  economic  importance,  it  is  known 
as  mealies,  probably  a  corruption  of  a  word  for  millet. 

Technical  names. — When  maize  came-  under  the  hand 
of  the  great  Swedish  systematist,  early  in  the  eighteenth 
century,  it  received  the  botanical  name  by  which  it  is 
still  known,  Zea  Mays.'^  In  consideration  of  the  nature 
of  the  plant  and  the  part  that  it  has  played  in  history, 
the  name  is  well  chosen.  Zea  is  from  the  Greek  name 
of  a  cereal,  and  this  is,  in  turn,  derived  from  a  verb 
meaning  ''to  live."  This  is  in  accord  with  Indian 
nomenclature,  many  versions  of  their  word  for  maize 
meaning  "that  which  sustains  us."  The  specific  name 
is  derived  from  the  aboriginal. 

An  endless  number  of  synonyms  have  come  into  more 
or  less  common  use  as  a  result  of  the  discovery  of  new 
varieties  supposed  to  be  worthy  of  specific  rank,  attempts 

'  Usage  with  regard  to  the  spelling  and  capitalization  of  the  specific 
name  is  not  uniform,  the  following  occurring  in  current  literature:  Mays, 
mays,  Mais,  juais,  Mais,  and  nmis.  The  first-named  form  seems  to  be 
preferred. 


6  THE  STORY  OF  THE  MAIZE  PLANT 

to  give  technical  names  to  agricultural  varieties,  the 
recognition  of  the  use  of  the  word  Mays  in  a  generic 
sense,  or  a  misunderstanding  of  the  nature  and  relation- 
ships of  the  species.  The  following  list  of  synonyms  is 
given  merely  for  purpose  of  illustration  and  is  in  no  way 
intended  to  be  complete: 

Zea  alba  Mill.  Zea  hidentata  Sturt. 

Zea  altissima  Gmel.  Zea  everta  Sturt. 

Zea  hirta  Bonaf.  Zea  indurata  Sturt. 

Zea  roslrata  Bonaf.  Zea  saccharata  Sturt. 

Zea  praecox  Pers.  Zea  tunicata  Sturt. 

Zea  Curagua  Molm.  Zea  Mays  tunicata  St.  Hil. 

Zea  canina  Wats.  Zea  Mays  rugosa  Bonaf. 

Zea  minor  Gmel.  Mays  zea  DC. 

Zea  macros  per  ma  Klotsch.  Mays  americana  Baum. 

Zea  cryptosperma  Bonaf.  Mays  vulgaris  Seringe 

Zea  ramosa  Gernert  Triticum  indicum  J.  Bauh. 

Zea  amylacea  Sturt.  Frumentum  turcicum  Blackw. 

The  aim  of  this  multiplication  of  nomenclature, 
especially  the  naming  of  varieties,  has  been  to  simplify 
and  elucidate  the  situation;  but  the  end  has  been  only 
ridiculous  confusion.  The  varieties  and  subspecies  named 
are  usually  based  upon  only  one  or  a  small  group  of 
characteristics  and  have  no  biological  identity.  It  is 
possible  for  a  single  individual  to  belong,  without 
question,  to  two  or  more  groups  named  co-ordinately, 
even  by  the  same  authority — a  situation  hardly  in  accord 
with  the  spirit  and  functions  of  the  binomial  system.  For 
example,  a  single  plant  of  podded  dent  corn  would  be  si- 
multaneously Zea  tunicata  Sturt.  and  Zea  indentata  Sturt. 
If  it  had  pistillate  flowers  in  its  tassel,  it  would  be  proper 
in  the  nomenclature  of  others  to  call  it  Zea  androgyna. 

An  almost  endless  number  of  agricultural  varieties 
are  already  in  existence,  and  new  ones  can  be  synthesized 


NAMES  AND  RELATIONSHIPS  7 

almost  at  will  by  hybridization;  and,  if  any  be  named, 
all  should  be.  Our  problem  is  not  so  much  to  find  names 
enough  for  all  as  it  is  to  stop  the  making  of  new  names 
soon  enough  to  enable  a  name  to  mean  anything.  The 
logical  thing  to  do  is  to  recognize  in  Zea  a  variable, 
complex  genus,  whose  primary  subdivisions  have  been 
irrevocably  lost  by  fusion  through  hybridization.  The 
only  name  not  overlapping  others  is  the  generalized 
Zea  Mays  L.,  or  its  synonyms  based  upon  other  generic 
names;  references  to  variations  and  to  agricultural 
varieties  may  better  be  made  by  structural  and  physio- 
logical terminology  than  by  Linnaean  binomials.  The 
success  with  which  this  method  is  followed  in  general 
botany  is  its  justification. 

Classification. — Maize  belongs  to  that  great  family 
of  monocotyledonous  plants  technically  designated  as 
Gramineae,  and  commonly  known  as  grasses.  The 
group,  as  a  whole,  is  too  well  known  to  require  a  detailed 
definition.  Most  of  its  members  are  herbaceous,  and 
they  exhibit  a  wide  range  of  variation  in  size,  form,  and 
habit.  Their  stems  are  round  or  flattened  and  marked 
by  definite  nodes;  the  internodes  are  usually  hollow.  The 
leaves  are  arranged  in  two  rows  on  the  stem.  The  flowers 
are  aggregated  in  compact  spikelets,  and  these  are  arranged 
in  many  types  of  inflorescence.  The  only  plants  with  which 
the  grasses  are  likely  to  be  confused  are  the  sedges,  and 
they  have  three-cornered  stems  and  three-ranked  leaves. 

The  tribe,  Tripsaceae,'  consists  of  seven  monoecious 
genera.  At  least  the  staminate  spikelets  are  in  pairs,  one 
of  each  pair  being  pediceled  and  the  others  sessile ;  they 

'  The  equivalent  of  the  old  tribe  Maydeae.  See  Hitchcock's  revision 
of  the  family  (79).     (Figures  refer  to  the  Bibliography,  pp.  227-35.) 


8 


THE  STORY  OF  THE  MAIZE  PLANT 


are  two-flowered  and  determinate,  the  upper  flower  in  the 
spikelet  being  the  more  advanced  in  development.  The 
pistiflate  spikelets  are  variable  in  arrangement  and  struc- 
ture, and  this  affords  a  basis  for  distinguishing  the  genera. 
Geographically  and  botanically  there  are  two  distinct 
groups  of  the  Tripsaceae.  While  there  are  many  points 
of  similarity  between  these 
groups,  there  are  also  sev- 
eral significant  differences; 
and  the  phylogenetic  rela- 
tionship between  them  may 
be  much  more  remote  than 
is  generally  believed. 

Four  genera — Coix, 
Sclerachne,  Chionachne, 
and  Polytoca^ — ^are  native 
of  various  parts  of  India, 
Indo-China,  Ceylon,  Java, 
Sumatra,Borneo,  Austraha, 
and  the  Philippines.  In  all 
these  genera,  the  fertile 
floret,  and  ultimately  the 
fruit,  is  inclosed  in  a  corne- 
ous to  stony  covering  con- 
sisting of  a  single  modified 
glume  or  foliar  sheath.  Coix  lachryma-Jobi  L.  is  the  best- 
known  species  of  the  group.  Under  the  common  name, 
"Job's  Tears,"  it  is  often  grown  in  gardens  as  an  orna- 
mental plant  and  for  its  fruits,  which  are  used  for  beads 
(Fig.  i).  It  is  now  widely  distributed  over  the  warmer 
parts  of  the  world  and  often  persists  as  an  escape  from 
cultivation. 


Inflorescence   of   Coix 


NAMES  AND  RELATIONSHIPS 


The  other  group  of  the  Tripsaceae  consists  of  three 
American    genera — Zea,     ;, 


Euchlaena,  and  Tripsa- 
cum.  Euchlaena  grows 
wild  in  Mexco  and  Cen- 
tral America  and  has 
been  introduced  as  a 
forage  plant  into  other 
warm  countries,  where  it 
is  known  as  "teosinte." 
It  seldom  matures  seeds 
farther  north  than  the  ex- 
treme southern  parts  of 
the  United  States.  Trip- 
sacum  has  a  much  wider 
range  than  Euchlaena, 
occurring  at  least  as  far 


Figs.  3-5.— Figs, 
escence  and  spikelets  of 
Tripsacum.  Fig.  5,  pistillate 
inflorescence  of  Euchlaena. 


Fig.  2. — Tripsacum  dactyloides,  cul- 
tivated on  the  campus  of  Indiana  Uni- 
versity. 

north  as  the  Ohio  River,  and 
extending  far  into  South  Amer- 
ica (Fig.  2). 

Maize  is  readily  distin- 
guished from  the  other  Ameri- 
can genera  by  the  pistillate 
inflorescence  and  the  fruit.  In 
Tripsacum  both  the  pistillate 
and  staminate  flowers  are 
borne  in  the  same  paniculate 
inflorescence,  but  in  differ- 
ent spikelets  (Figs.  3,  4).     In 


THE  STORY  OF  THE  MAIZE  PLANT 


the  other  two  genera  the  staminate  flowers  occur  in  a 
terminal  panicle  (Figs.  6,  7)  and  the  pistillate  in  lateral 
spikes.  The  pistillate  in- 
florescence of  Euchlaena 
(Fig.  5)  resembles,  in  some 
respects,  that  of  Zea,  and 
the  generic  distinctions  are 
sometimes  complicated  by 
the  occurrence  of  mixed 
inflorescences;  but  no  one 
who  has  ever  seen  an  ear 
of  corn  has  any  difficulty 
in  distinguishing  maize 
from  its  near  relatives. 
Maize  is  generally  regarded 
as  the  most  highly  speciaHzed  grass  plant  in  existence. 


Figs.  6,  7. — Staminate  panicl 
and  spikelets  of  Euchlaena. 


CHAPTER  III 
HISTORY  AND  GEOGRAPHICAL  DISTRIBUTION 

There  is  some  doubt  as  to  when  maize  was  first  seen 
by  civiHzed  man.  An  old  Scandinavian  record  states 
that  the  Northmen,  on  one  or  more  of  their  visits  to 
North  America  nearly  a  thousand  years  ago,  found 
"self-sown  cornfields,"  and,  on  one  occasion,  a  wooden 
shed  for  the  storage  of  grain.  This  brief  mention  has 
been  taken  by  many  authorities  as  the  first  account  of 
maize  to  be  written  by  a  white  man.  But  it  seems  that 
a  thing  so  striking  as  a  field  of  corn  would  have  called 
for  a  more  extended  discussion.  The  fact  that  it  was 
passed  by  merely  as  "corn" — in  sharp  contrast  with  the 
enthusiasm  with  which  later  explorers  described  it — 
would  lead  to  the  belief  that  the  plant  they  saw  was 
more  like  the  cereals  of  Europe;  and,  if  so,  it  was  not 
maize. 

The  southern  limit  reached  by  the  Northmen  is 
still  a  matter  of  some  doubt.  If,  as  some  beheve,  they 
did  not  explore  farther  south  than  the  mouth  of  the  St. 
Lawrence,  they  probably  did  not  come  within  the  range 
of  maize.  Moreover,  the  fact  that  the  cereal  was 
mentioned  as  "self-sown"  points  to  its  being  some  plant 
that  grew  wild,  and  it  is  very  improbable  that  wild  maize 
would  have  been  found  in  northeastern  North  America 
if  found  at  all.  The  plant  seen  by  the  Northmen  was 
more  probably  some  wild  grass  resembhng  wheat  or 
rye  (2,  59,  16).' 

'  References  given  in  this  way  are  to  the  Bibliography,  pp.  227-35. 


12  THE  STORY  OF  THE  MAIZE  PLANT 

Discovery  by  Columbus. — The  first  authentic  account 
of  maize  is  that  given  by  Columbus  and  his  companions 
on  the  first  voyage  of  discovery.  The  record  of  this 
voyage  tells  of  finding  the  plant  in  cultivation  in  the 
West  Indies  and  records  its  native  names,  from  which 
the  word  maize  has  been  derived.  It  is  also  recorded 
that,  on  the  occasion  of  the  first-known  celebration  of 
Christmas  in  America,  bread  made  from  maize  was  one 
of  the  main  constituents  of  the  dinner.  Columbus  and 
his  men  were  enthusiastic  in  their  praises  of  this  food, 
and  probably  partook  of  it  all  the  more  heartily  because 
they  could  not  screw  their  courage  up  to  the  point  of 
eating  with  a  relish  the  roasted  iguana  which  constituted 
the  meat  course. 

The  explorations  of  the  sixteenth  and  seventeenth 
centuries  showed  the  range  of  the  species  to  extend 
from  Chile  and  Argentina  on  the  south  to  the  Great 
Lakes  region  on  the  north  (Fig.  8).  In  all  favorable 
locations  in  this  vast  region,  it  was  found  in  an  endless 
variety  of  forms  and  in  various  states  of  cultivation, 
but  in  no  nook  or  corner  of  either  continent  has  the  wild 
form  ever  been  found.  In  historic  times  the  species  has 
been  completely  dependent  upon  man  for  its  perpetuation. 

Introduction  into  Europe. — In  the  meantime,  it  had 
been  introduced  into  Europe,  first  from  the  West  Indies 
by  the  Spaniards,  and  a  short  time  later  from  Peru. 
From  Spain  it  was  taken  into  other  countries,  new 
introductions  being  made  from  America  all  the  while, 
and,  in  the  sixteenth  century,  we  find  it  grown  as  a 
garden  curiosity  in  Spain,  Italy,  France,  Germany,  and 
England.  With  the  immediate  recognition  of  the  plant's 
usefulness,    there    began    a    rapid    distribution,    which 


Fig.  8. — Distribution  of  maize  in  aboriginal  America.  The  densely 
shaded  portion  in  Mexico  and  Central  America  is  the  probable  place  of 
origin  of  maize.  In  other  portions  of  this  and  the  other  maps  showing 
distribution,  the  density  of  the  shading  indicates  the  relative  importance 
of  maize  as  a  crop  plant.  The  data  included  in  this  map  are  from  Harsh- 
berger  (74),  Wissler  (168),  and  other  sources. 


14 


THE  STORY  OF  THE  MAIZE  PLANT 


ultimately   made  it  a  common   agricultural   staple  in 
every  part  of  the  world  that  afforded  it  a  favorable 


Fig.  9. — Present  distribution  of  maize  in  North  America.  The  data 
included  in  the  maps  showing  the  present  distribution  of  maize  were 
secured  largely  from  publications  of  the  United  States  Department  of 
Agriculture. 


climate  and  soil.  The  Portuguese  distributed  it  along 
the  coast  of  Africa,  and  probably  introduced  it  into 
China,  and  it  made  its  appearance  in  India  at  about  the 
same  time. 


HISTORY  AND  GEOGRAPHICAL  DISTRIBUTION     15 

Present  distribution. — Today  maize  is  extensively 
grown  in  Mexico,  Argentina,  Hungary,  Roumania,  Italy, 
Russia,  Egypt,  India,  and  South  Africa;   and,  to  a  less 


Fig.  10.— Present  distribution  of  maize  in  South  America 


extent,  in  Canada,  Peru,  Chile,  Central  America,  Spain, 
Portugal,  France,  Germany,  China,  Japan,  Australia, 
and  the  Philippines  (Figs.  9-13).  But  it  is  still  princi- 
pally an  American  crop,  the  United  States  producing 


iG.  n. — Present  distribution  of  maize  in  Europe 


Fig.  12. — Present  distribution  of  maize  in  Asia 


HISTORY  AND  GEOGRAPHICAL  DISTRIBUTION     17 

each  year  three  times  as  much  as  all  other  countries 
together. 

Place  of  origin. — From  time  to  time  apparent  evi- 
dences have  been  found  that  maize  was  a  native  of  other 


Fig.  13. — Present  distribution  of  maize  in  Africa 


countries  than  America,  but  none  of  these  have  stood 
the  ultimate  test.  An  ear  of  corn  is  said  to  have  been 
found  in  a  tomb  in  Egypt,  but  this  occurrence  is  supposed 
to  have  been  the  work  of  an  impostor.  Nothing  has 
been  found  in  Egyptian  art  or  literature,  or  elsewhere 
in  the  ruins,  to  indicate  that  the  plant  was  known  there 


THE  STORY  OF  THE  MAIZE  PLANT 


in  ancient  times.     An 
of  maize  was  brought 


Fig.  14. — The  first  pub- 
lished figure  of  maize.  From 
an  edition  of  the  Pen-tsao- 
kung-mu,  published  prob- 
ably about  1597.  The  three 
symbols  of  the  legend  con- 
stitute the  modern  Chinese 
word  for  maize,  Shu-cho-yii. 
Their  literal  meaning  is :  shit, 
millet,  or  cereal;  Cho,  Szech- 
wan,  a  province  of  Western 
China;  and  yii,  a  gem,  or 
precious  stone.  To  the  Chi- 
nese of  that  day,  then,  maize 
was  known  as  a  cereal  which 
resembled  a  precious  stone 
and  came  from  Szechwan. 
For  the  literal  translation  of 
these  terms,  I  am  indebted  to 
one  of  my  former  students, 
Mr.  C.  C.  Feng.  Figure  from 
Bonafous'  copy  of  original. 

lion  as  to  the  manner 


old  account  as  to  how  the  seed 
to  Europe  during  the  Crusades 
has  been  found  to  be  unreli- 
able. If  maize  had  been  intro- 
duced at  this  time,  or  had  been 
known  anywhere  in  the  Old 
World  at  this  time,  it  would  be 
difficult  to  explain  why  it  did  not 
gain  the  rapid  dissemination  that 
characterized  it  later. 

Several  accounts  in  Chinese 
literature  of  the  sixteenth  century 
have  been  cited  as  evidence  that 
maize  was  known  in  China  in 
pre-Columbian  times.  The  one 
figure  given  in  a  book  published 
between  1552  and  1578,  or  possi- 
bly as  late  as  1637,  might  as  well 
be  taken  for  some  other  grass 
than  maize  were  it  not  for  the 
accompanying  text  (Fig.  14). 
The  dates  of  this  and  other  refer- 
ences are  doubtful,  and  there  has 
been  cited  no  authentic  mention 
of  maize  in  Chinese  literature 
definitely  known  to  antedate  the 
appearance  of  the  Portuguese  in 
the  Orient  in  15 16.  But  its  fre- 
quent mention  in  the  literature 
of  the  sixteenth  century,  and  the 
absence  of  any  definite  informa- 
of  its  introduction,  indicate  long 


HISTORY  AND  GEOGRAPHICAL  DISTRIBUTION     19 

acquaintance  with  it;  and  the  occurrence  in  Chinese 
varieties  of  certain  vegetative,  floral,  and  endospermic 
characteristics  not  known  in  other  varieties,  points  to 
a  long  period  of  isolation.  The  American  origin  of  the 
plant  is  seldom  questioned  today,  but  this  does  not  pre- 
clude the  remote  possibility  of  its  introduction  into  Asia 
before  1492.' 

At  the  time  of  the  discovery  of  America,  maize  was 
the  staple  food  plant  of  both  continents  and  undoubtedly 
the  central  factor  of  aboriginal  civilization.  The  wonder 
that  it  excited  in  the  early  explorer,  and  the  rapidity 
with  which  it  found  a  place  in  the  economic  life  of  the 
Old  World  after  its  introduction  early  in  the  sixteenth 
century,  are  strong  indications  that  it  was  previously 
unknown  there.  These  are  ably  supported  also  by 
the  botanical  evidences,  all  of  which  show  that  the 
nearest  relatives  of  maize  were  undoubtedly  of  American 
origin. 

The  high  degree  of  maize  culture  practiced  in  ancient 
Mexico  and  Peru  has  led  to  the  belief  on  the  part  of 
some  historians  that  the  plant  had  a  double  origin,  one 
strain  being  evolved  in  North  America  and  the  other  in 
South  America.  An  additional  basis  for  this  idea  is 
found  in  the  fact  that  pod  corn,  which  was  once  believed 
to  be  very  near  the  wild  form  in  character,  has  been 
reported  from  localities  as  widely  separated  as  Paraguay 
and  the  Rocky  Mountains. 

'  The  evidences  on  all  sides  of  this  interesting  question  are  reviewed 
by  Collins  (22)  in  connection  with  the  description  of  a  peculiar  variety 
of  corn  recently  discovered  in  China.  The  endosperm  of  this  variety 
is  "waxy";  the  leaves  stand  erect  and  assume  an  asymmetrical  arrange- 
ment; and  the  silks  precede  the  ends  of  the  husks  in  their  emergence 
from  the  leaf  sheath  subtending  the  ear. 


20  THE  STORY  OF  THE  MAIZE  PLANT 

But  there  seems  to  be  no  necessity  for  the  radical 
assumption  of  a  duplicate  origin,  and  the  botanical 
evidence  of  such  an  occurrence  is  entirely  lacking.  All 
kinds  of  maize,  from  all  parts  of  both  continents,  are 
alike  in  all  fundamental  characteristics.  Pod  corn 
frequently  appears  by  regressive  variation  in  any  variety 
and  is  no  longer  believed  to  be  the  bearer  of  unchanged 
prototypic  characters  down  to  the  present. 

The  fragmentary  history  of  the  early  migrations  of 
aboriginal  tribes,  and  the  evolution  of  the  vocabulary 
related  to  maize  and  its  associations,  point  to  a  single 
origin  in  some  central  location.  Indian  literature  is 
never  a  very  dependable  source  of  exact  information, 
but  many  legends  tell  of  the  introduction  of  maize 
culture  from  tribes  in  the  general  direction  of  Central 
America.  One  elaborate  myth  of  the  Mayas,  of  the  low, 
forested  foothills  of  Yucatan  and  Central  America,  tells 
how  certain  earthly  deities,  or  supermen,  gave  to  the 
barbarian  tribes  the  seed  of  maize  and  taught  them  its 
culture  and  uses.'  This  seems  to  be  the  most  nearly 
scientific  account  of  this  event  that  the  Indian  has  ever 
given  the  white  man.  In  the  versions  of  this  tradition 
in  most  tribes,  the  supernatural  figures  so  prominently 
as  to  destroy  or  obscure  any  atom  of  fact  that  may  origi- 
nally have  been  present,  but  the  geographical  location  of 
the  incident  is  probably  the  least  likely  to  be  perverted 
in  the  telling. 

As  to  the  exact  locality  that  was  the  birthplace  of 
the  species,  there  may  still  be  room  for  controversy; 
but  the  information  now  at  hand  points  suggestively  to 
the   plateaus    and    foothills    of    Central   America    and 

'  See  pp.  I9Q-200. 


HISTORY  AND  GEOGR.\PHICAL  DISTRIBUTION     21 

southeastern  Mexico  (Fig.  8).  A  plant  originating  in 
this  region,  and  soon  becoming  dependent  upon  cultiva- 
tion for  perpetuation  and  improvement,  might  reasonably 
be  expected  to  attain  its  greatest  prominence  in  the  more 
favorable  agricultural  regions  of  Peru  and  central 
Mexico. 

The  claims  of  other  places  are  not  without  founda- 
tion. Certain  localities  in  the  Andes  have  as  favorable 
ecological  conditions  as  those  of  Mexico  and  Central 
America,  and  Indian  traditions  might  well  be  disregarded 
if  inconsistent  with  more  reliable  data.  But  against  this 
stands  the  limited  range  of  teosinte,  which  has  until 
recent  years  been  uninfluenced  by  man,  and  has  about 
the  same  distribution  as  should  be  expected  of  maize, 
were  it  not  a  useful  plant. 


CHAPTER  IV 
BOTANICAL  ORIGIN 

Maize  stands  almost  alone  amon^the  cereals  as  a 
cultivated _plant  whose  wild  prototype  is  unknown. 
For  most  of  our  common  cultivated  plants  there  is  a 
corresponding  wild  form,  which,  on  being  brought 
under  cultivation^  gives  promise  of  resembling  its 
cultivated  relative,  and  toward  which  the  cultivated 
forrn  tends  to  reverton  its  escape  from  cultivation. 
But  no  plant  has  eveFlDeen  found  exhibiting  such 
relationshig_^wkhjnaizej_and  it  has  been  an  interesting 
problem  for  the  botanist  to  build  a  bridge  of  theory 
from  modern  maize  back  to  the  point  where  its  relation- 
ships are  evident. 

Sources  of  information. — There  is  available  no  direct 
information  as  to  the  nature  of  this  interesting  cereal 
previous  to  the  last  four-and-a-half  centuries.  How 
much  of  its  evolution  was  due  to  primitive  agriculture, 
and  how  much  merely  to  natural  conditions,  we  have 
no  means  of  knowing.  In  fact,  it  would  be  difficult  to 
say  just  when  man's  activities  might  cease  to  be  called 
an  element  of  natural  environment  and  begin  to  be 
dignified  with  the  name  agriculture.  At  any  rate,  if 
man  was  present  at  the  birth  of  the  species,  he  left 
of  the  event  no  dependable  record.  The  vagueness 
of  most  of  the  Indian  myths  on  this  point,  and  the 
promiscuous  mingling  of  the  natural  and  the  super- 
natural, indicate  much  more  imagination  than  obser- 
vation. 


BOTANICAL  ORIGIN  23 

In  the  absence  of  any  direct  evidence,  then,  we  must 
have  recourse  to  the  circumstantial.  For  the  solution 
of  our  problem,  we  may  accept  any  theory  that  is  con- 
sistent with  facts;  we  must  reject  all  that  are  out  of 
harmony  with  facts;  and  our  discrimination  among  the 
consistent  explanations  must  be  guided  by  what  seems 
reasonable,  and  by  the  extent  to  which  each  theory 
has  made  use  of  all  the  available  data. 

The  information  from  which  our  theory  is  to  be 
deduced  is  not  so  extensive  in  this  instance  as  in  the  case 
of  many  other  plants,  but  it  is  sufficiently  significant  to 
warrant  some  definite  conclusions. 

Geology  and  archaeology  give  us  practically  no  clue  to 
the  mystery.  Only  a  few  fossil  remains  of  maize  have 
been  found,'  and  they  are  practically  identical  in  nature 
with~thgjlvin^_plant.  Owing  to  the  Indian  custom  of 
burying  food  with  the  d_ead,  and  to  the  abundance  of  the 
grain  around  Indian  settlements,  an  enormous  amount  of 
material  has  been  collected  from   tombs,  buried  huts, 


and  the  charred  remains  of  camp  fires.^  The  structures 
left  by  the  Mound  Builders  of  the  Mississippi  Valley, 
and  the  tombs  of  ancient  Peru,  have  been  especially 
fruitful  sources.  But  not  a  single  specimen  has  ever 
been  found  embodying  any  characteristic  not  present 
in  the  living  plant. 

'  These  are  discussed  by  Collins  (31). 

^  Much  of  the  material  that  has  been  dug  up  from  Indian  ruins  owes 
its  preservation  to  its  having  been  charred  by  fire.  These  ears  were  doubt- 
less, in  many  instances,  the  small  ones  that  had  been  overlooked  in  husk- 
ing, or  rejected  as  too  insignificant  to  harvest.  When  the  stalks  were 
later  used  as  fuel,  the  ears  were  often  only  partly  burned.  It  is  probable, 
too,  that  small,  or  partly  decayed,  ears  that  had  been  husked  were  at 
times  used  for  fuel  and  only  partly  burned. 


24  THE  STORY  OF  THE  IVIAIZE  PLANT 

Maize  is  one  of  the  most  variable  of  the  cereals; 
and  this  variability  finds  erQresgJQn  not  only  in  the 
existence  of  an  endless  number  of  agricultural  strains, 
but  also  in  the  sporadic  appearance  of  anomalies.  Many 
of  these  freaks  seem  to  embody  imitations  of  lost  ancestral 
characteristics.  But  mutations  may  be  either  pro- 
gressive or  regressive,  and  the  occurrence  of  these 
teratological  forms  cannot  be  used  as^yidence  of  the 
course  of  evolution,  unless  we  have  other  proof  that  they 
are  returns  to  remote  ancestral  conditions.  Moreover, 
we  must  avoid  the  common  error  of  assuming  that  a 
particular  characteristic  under  consideration  is  regressive 
merely  because  it  is  associated  in  the  same  individual 
with  other  characteristics  in  which  reversion  is  evident. 

The  methods  of  civilized  agriculture  have  failed  to 
do  more  than  indicate  the  general  trend  of  evolution  in 
the  plant.  Breeding  has  eUminated  a  few  superfluous 
organs,  increased  size  and  vigor,  and  concentrated  the 
fruit  into  one  or  only  a  few  ears;  and  these  elements  of 
specialization  are  probably  a  continuation  of  the  process 
that  nature  and  the  Indian  have  been  promoting  for 
ages.  The  genetic  researches  on  maize  in  the  past 
twenty  years  have  disclosed  much  of  the  evolutionary 
significance,  and  shown  much  about  the  order  of  appear- 
ance of  many  of  the  plant's  most  striking  characteristics, 
but  these  methods  have  really  done  little  toward  indicat- 
ing the  connecting  links  between  maize  and  its  past. 
One  of  the  confusing  elements  that  have  entered  into  the 
problem  has  been  the  suggestive  appearance  of  the  hybrids 
between  maize  and  teosinte  (Fig.  15).  With  proper 
manipulation,  these  hybrids  may  be  made  to  show  in 
the  form  of  the  ear  a  graded  series  of  steps  between  maize 

fltOPERTY  UBRART 


BOTANICAL  ORIGIN 


25 


l'"iG.  15. — A  hybrid  between  maize  and  teosinte.     In 
habit  this  plant  closely  resembles  pure  teosinte. 


26 


THE  STORY  OF  THE  MAIZE  PLANT 


and  teosinte  (Figs.  16-18).  But  these  are  the  result 
of  blended  effects  in  hybrids,  and  not  steps  in  an  evolu- 
tionary series. 

In  both  the  vegetative  and  floral  structures  of  maize, 
there  have  been  disclosed,  by  histological  methods, 
numerous  rudimentary  organs.  From  their  behavior 
during  the  development  of 
the  plant,  we  beheve  these 
to  be  the  remnants  of  parts 
that  have  ceased  to  func- 
tion in  past  generations,  and 
not  the  forerunners  of  parts 
that  are  to  be.  Many  of 
the  anomalies  occurring  in 
corn  result  from  the  func- 
tioning and  full  develop- 
ment of  these  vestigials. 
Such  occurrences  are  to  be 
regarded  as  true  reversions. 
A  detailed  morphologi- 
cal examination  of  Zea,  in 
comparison  with  Euchlaena 
and  Tripsacum,  and  taking 
into  consideration  the  rudi- 
mentary organs  and  significant  anomalies  of  the  three 
genera,  shows  a  remarkable  similarity  in  structural  plan, 
and  furnishes  a  definite  basis  for  working  out  the  true 
phylogenetic  relationships.  A  superficial  view  of  char- 
acteristics, however,  promises  only  a  precarious  basis  for 
philosophic  consideration. 

The  evolution  of  maize. — Since  the  introduction  of  the 
maize  plant  to  science,  many  attempts  have  been  made 


a 


16  17  18 

Figs.  16-18. — Pistillate  spikes 
of  a  first-generation  hybrid  between 
maize  and  teosinte. 


BOTANICAL  ORIGIN  27 

to  explain  logically  its  botanical  origin.  Some  of  these 
explanations  are  clearly  defective,  but  others  are  more 
consistent  with  facts.  Each  is  to  be  considered  a  reflec- 
tion of  what  was  known  of  the  plant  and  of  the  principles 
of  evolution  at  the  time  at  which  the  theory  was  proposed. 

Much  time  has  been  spent  in  an  unsuccessful  search 
for  wild  maize.  No  one  seems  ever  to  have  considered 
seriously  any  of  the  oriental  species  of  the  Tripsaceae 
as  the  wild  progenitor;  geographical  separation  and 
significant  botanical  differences  indicate  only  a  distant 
relationship.  In  the  discovery  of  teosinte  it  seemed 
certain  that  wild  maize  had  been  found.  The  general 
habit  of  the  plant,  and  many  details  of  stem,  leaf,  and 
inflorescence,  are  suggestive  of  maize;  and  the  scientific 
literature  of  that  day  includes  references  to  teosinte  as 
wild  maize.  But  this  idea  has  long  ago  been  abandoned 
by  most  investigators. 

Burbank  was  confident  of  this  relation  between 
maize  and  teosinte,  and  some  of  the  latest  authentic 
expositions  of  his  work  figure  a  fine  ear  of  yellow  dent 
corn  by  the  side  of  its  alleged  pigmy  ancestor,  the  "ear" 
of  teosinte.'     His  followers  go  still  farther,  and  picture 

'  A  recent  dissertation  of  this  type  by  Robert  H.  Moulton,  in  the 
magazine  section  of  the  (St.  Louis)  Post-Dispatch,  was  given  wide  pub- 
licity by  a  review  in  the  Literary  Digest  for  July  q,  192  i,  and  in  one  or 
two  subsequent  minor  articles.  Here  it  is  alleged  that,  starting  with 
wild  teosinte  in  1903,  Burbank  had,  by  selecting  for  eighteen  generations, 
produced  maize.  The  lajonan  will  doubtless  hail  this  as  a  notable  addi- 
tion to  the  long  list  of  Burbank's  vegetable  "creations."  But  the 
figures  accompanying  this  article,  like  the  color  photographs  included 
in  certain  publications  of  the  Luther  Burbank  Society,  indicate  that 
the  plant  with  which  Burbank  started  was  not  teosinte  at  all,  but  a 
hybrid  between  teosinte  and  maize.  Mass  selection,  intelligently  carried 
out  on  the  descendants  of  this  hybrid,  might  reasonably  be  expected 
to  result  in  a  plant  approaching  maize  in  form.     And  an  approach  to 


28  THE  STORY  OF  THE  IMAIZE  PLANT 

in  graphic  terms  the  imaginary  "creation"  of  maize 
in  past  ages  at  the  hand  of  some  Montezuma  Burbank, 
by  the  selection  of  favorable  variations  of  teosinte. 
But,  in  spite  of  the  popular  following  that  this  kind  of 
logic  may  win,  it  becomes  a  mere  jumble  of  imagination 
when  measured  by  scientific  standards. 

Teosinte  and  maize  are  both  highly  specialized,  but 
in  different  ways;  and  teosinte  is  far  too  highly  special- 
ized in  some  ways  to  be  logically  considered  the  ancestor 
of  maize.  No  one  dealing  with  pure  strains  by  carefully 
guarded  methods  has  ever  been  able  to  show,  as  a  result 
of  cultivation  or  selection,  any  tendency  for  teosinte  to 
become  maizelike  or  of  maize  to  revert  to  teosinte. 

A  little  more  than  thirty  years  ago,  it  was  discovered 
that  the  natives  of  some  parts  of  Mexico  had  a  peculiar 
kind  of  corn  known  as  "maiz  de  coyote."  This  variety  had 
many  apparently  primitive  characteristics,  and  at  least 
two  American  botanists'  described  it  as  wild  maize;  but 
further  investigation  showed  that  its  synthesis  by  crossing 


maize  is  really  all  that  Burbank  accomplished,  for  the  superior  forage 
properties  claimed  for  the  new  "corn,"  and  the  photographs  of  the  final 
form,  show  that  many  of  the  characteristic  features  of  teosinte  have 
not  been  eliminated  from  the  hybrid  by  the  selective  process.  That 
changes  have  been  wrought  in  the  plant  cannot  be  denied,  and  the  new 
form  may  well  be  the  superior  of  teosinte  as  a  forage  plant;  but  the  ex- 
periment affords  not  an  atom  of  fact  concerning  the  ancestry  of  maize. 
The  loophole  in  this  experiment  is  in  the  nature  of  the  plant  used  as  its 
basis;  nothing  is  said  as  to  the  source  from  which  it  was  obtained,  and  the 
only  description  given,  namely,  the  photograph,  indicates  that  it  was  not 
what  it  was  thought  to  be  during  the  experiment.  If  we  wish  to  get 
merely  a  new  useful  plant,  no  special  attention  need  to  be  paid  such 
things  as  the  exact  origin  of  our  material;  but  if  we  are  seeking  a  new 
principle,  such  details  are  of  fundamental  importance. 

»  Watson  (148)  and  Harshberger  (74). 


BOTANICAL  ORIGIN  29 

maize  and  teosinte  and  back-crossing  with  maize  had 
often  been  accompKshed  by  certain  Mexican  botanists.' 

When  the  supposed  wild  maize  was  found  to  be  a 
mongrel,  it  was  conceived,  by  some  twist  of  logic,  that 
maize  might  have  arisen  as  a  hybrid  between  teosinte 
and  some  other  grass. 

One  theory  pictured  the  other  parent  as  a  superior 
form  of  teosinte  that  had  been  produced  by  cultivation.^ 
But  the  necessity  for  this  indirect  method  of  origin  has 
never  been  made  clear,  and  the  theory  has  gained  little 
support.  It  would  be  as  easy,  and  much  more  direct, 
for  teosinte  to  throw  off  immediately  the  mutant  maize 
as  to  produce  a  mutant  which  would  hybridize  with 
the  parent  species  and  produce  maize. 

According  to  another  form  of  the  hypothesis  of  hybrid 
origin,-^  maize  originated  in  a  cross  between  teosinte  and 
some  unknown  grass  having  the  general  character  of 
pod  corn.  But  if  this  unknown  grass  had  the  general 
characters  of  pod  corn,  it  would  itself  have  had  the  gen- 
eral characters  of  ordinary  maize,  and  the  hybridization 
would  have  been  unnecessary.  Since  the  question  of  the 
origin  of  maize  has  been  rather  generally  disregarded 
in  recent  years,  except  by  those  supporting  the  theory  of 
hybrid  origin,  this  idea  has  held  a  more  prominent  place 
than  it  merits.  But  many  have  accepted  it  with  reluc- 
tance as  being  the  only  explanation  having  a  prominent 
place  in  the  literature. 

This  theory  is  illogical  and  unnecessarily  imaginative, 
but  it  is  also  insecurely  founded  morphologically.  It 
depends  largely  upon  the  predicated  intermediate 
position  of  maize  between  the  highly  speciahzed  teosinte 

'  See  Harshberger  (75).  ^  im^  3  Collins  (24). 


30  THE  STORY  OF  THE  MAIZE  PLANT 

and  the  more  simple  pod  corn.  But  a  better  morpho- 
logical analysis  than  was  available  when  the  theory- 
was  first  proposed  shows  less  difference  in  specialization 
than  was  formerly  supposed;  and  the  definition  of  pod 
corn  is  determined  more  by  the  needs  of  the  theory 
than  by  any  exact  identity.  Hybrids  between  pod 
corn  and  teosinte  have  never  been  shown  to  give  the 
significant  evidence  that  would  be  expected  under  the 
assumed  conditions.  With  the  recognition  of  these 
shortcomings,  the  chimerical  hypothesis  fails.  The  idea 
came  into  being  as  scarcely  more  than  a  guess  in  answer 
to  a  question,  and  the  facts  and  fancies  that  have  been 
marshaled  in  its  support  fall  far  short  of  its  substantiation. 

The  clearest  and  most  reasonable  deduction  from  the 
facts  at  hand  is  that  Zea,  Euchlaena,  and  Tripsacum 
descended  directly  and  independently,  in  so  far  as 
hybridization  is  concerned,  from  a  common  ancestor  now 
extinct.  No  morphological  feature,  genetic  peculiarity,  or 
historical  fact  is  known  to  introduce  any  factor  of  inconsist- 
ency, and  the  theory  is  reasonable,  orthodox,  and  simple. 

Certain  other  genera  of  grasses  very  probably  had 
the  same  origin  as  these  three,  but  more  or  less  artificial 
criteria  of  classification  have  thus  far  relegated  them  to 
a  neighboring,  and  presumably  more  remotely  related, 
tribe,  the  Andropogoneae. ' 

'  It  is  unfortunate,  for  the  cause  of  morphology,  that  monoecism 
was  adopted  as  a  unifying  characteristic  in  forming  the  Tripsaceae. 
Elsewhere  in  the  Gramineae,  as  in  Poa,  Eragrostis,  and  the  Chlorideae, 
even  dioecism  is  not  given  such  significance,  and  it  is  evident  in  the  Trip- 
saceae that  monoecism  has  arisen  independently  in  different  genera. 
A  thorough  morphological  study  of  the  Andropogoneae  may  ultimately 
show  that  maize  and  the  sorghums  represent  one  branch,  and  Tripsacum, 
Euchlaena,  and  Rottbocllia  another,  of  the  descendants  of  some  common 
stock,.    The  oriental  Tripsaceae  constitute  almost  a  separate  tribe. 


BOTANICAL  ORIGIN  31 

The  prototype  of  maize. — The  similarities  in  structure 
among  these  three  American  genera  of  the  Tripsaceae 
make  possible  a  consistent  mental  picture  of  the  hypo- 
thetical ancestor  of  all  of  them.  If,  in  individual 
representatives  of  these  three  respective  genera,  the 
rudimentary  organs  whose  vestiges  are  present  could  be 
induced  to  make  full  development  and  resume  their 
former  functions,  the  three  forms  would  converge  toward 
a  single  one  resembling  the  prototype. 

The  common  ancestor  was  probably  a  herbaceous 
perennial.  Its  branching  culms  arose  in  tufts  from  a 
mat  of  short  rhizomes,  and  the  ramifications  branched 
again  and  again  at  all  but  the  uppermost  nodes.  Diffuse 
panicles  of  paired  spikelets  terminated  all  the  branches. 
Each  spikelet  had  two  perfect  flowers.  The  pistil  had 
^wo  styles. 

Embodied  in  this  species  was  a  tendency  toward 
specialization  by  the  abortion  of  parts.  This  has  found 
its  best  expression  in  the  evolution  of  monoecism. 
The  manner  in  which  monoecism  came  about  differ- 
entiated Tripsacum  from  Euchlaena  and  Zea.  The 
latter  two  differed  from  each  other  in  the  manner  of 
the  reduction  of  their  panicles.  With  the  adoption  of 
the  annual  habit,  the  rhizomes  disappeared,  and  the 
tuft  of  culms  was  reduced  to  a  single  axis  and  its 
branches. 

At  the  chmax  of  evolution  in  maize,  the  process  of 
abortion  has  eliminated  all  the  lateral  branches  except 
that  bearing  the  ear,  and  has  left  but  two  inflorescences. 
A  detailed  discussion  of  the  possible  steps  in  these 
processes  can  be  most  advantageously  included  in  the 
morphology  of  the  various  organs  of  the  plant. 


CHAPTER  V 
STRUCTURE  AND  GERMINATION  OF  THE  SEED 

In  size,  shape,  color,  and  external  form,  the  grain  of 
corn  is  variable,  but  it  constantly  possesses  three  funda- 
mental parts:  a  tough,  dry,  membranous  covering;  an 
embryonic  corn  plant;  and  a  reserve  food  supply 
(Fig.  19). 

The  protective  covering  consists  of  the  seed  coat 
proper  and  the  matured  wall  of  the  ovary ;  it  is  the  testa 
and  the  pericarp  combined.  At  one  end  of  the  grain 
the  pericarp  is  marked  by  the  minute,  beaklike  base  of 
the  silk  that  was  attached  during  development.  At  the 
other  end  it  merges  into  the  chitinous  pedicel  by  which 
the  grain  was  attached  to  the  cob. 

A  large  part  of  the  seed  is  made  up  of  the  endosperm. 
The  cells  of  this  tissue  are  richly  stored  with  food  mate- 
rials for  the  nourishment  of  the  young  plant. 

Imbedded  in  one  side  of  the  endosperm,  and  in  contact 
with  the  seed  coat,  is  the  embryo.  Structurally,  it 
consists  of  a  short  central  axis  terminated  above  by  the 
plumule  and  below  by  the  radicle,  and  bearing  from  its 
middle  portion  the  large  cotyledon. 

The  plumule  is  the  bud  from  which  are  to  develop  the 
stem  and  leaves  of  the  seedling.  It  is  completely  inclosed 
in  the  firm,  cylindrical  coleoptile,  or  plumule  sheath. 

The  radicle  consists  of  the  primary  root  and  its  cap 
and  the  inclosing  coleorhiza,  or  root  sheath. 

The  cotyledon  is  doubtless  the  first  leaf  of  the  embryo. 
It  is  laterally  attached  to  the  central  axis,  which  it  partly 


STRUCTURE  AND  GERMINATION  OF  THE  SEED     S3 


surrounds  with  its  two  lateral  folds.     The  portion  of  the 
cotyledon  in  contact  with  the 
endosperm   is    the    scutellum. 

The  middle  portion  of  the 
embryonal  axis,  to  which  the 
cotyledon  is  attached,  is  the 
very  short  stem  of  the  embryo. 
Arising  from  it  are  the  pri- 
mordia  of  two  or  more  second- 
ary roots.  A  meristematic  area 
almost  opposite  the  cotyledon 
probably  represents  a  rudimen- 
tary cotyledon,  the  second 
embryonal  leaf.  This  is  the 
equivalent  of  the  epiblast  of 
some  grasses.' 

Viability. — ^The  seeds  of 
maize  vary  greatly  as  to  term  of 
viability.  They  are  capable  of 
germination  as  soon  as  mature, 
no  after-ripening  process  or 
other  period  of  dormancy  being 
necessary.  In  warm,  moist 
weather  even  immature  grains 
often  sprout  while  still  on  the 
ear  inside  the  husk,  and  very  Fig.  19. 
immature  grains  may  be  dried    ^^^^^  °^.  ^  ^rain  of  dent  com. 

°  -^  r,    pericarp;    h,    endosperm; 

and  later  made  to  germinate.        c,  cotyledon;    Ps,   plumule 
Retention  of  vitality  by  the    '^""^^l  (coleoptile) ;  Pi,  plum- 

-^      -^  ule;  K,  root;  Rs,  root  sheath 

ripe  seeds  depends  largely  upon    (coleorhiza). 

'  A  more  detailed  account  of  the  embryo  will  be  found  in  chap,  xix, 
where  its  development  is  treated. 


-Longitudinal  sec- 


34  THE  STORY  OF  THE  MAIZE  PLANT 

the  variety,  but  chiefly  upon  the  conditions  under  which 
the  seeds  are  matured  and  to  which  they  are  subjected 
after  maturity.  j\Iost  grains  of  corn  retain  their  vitaHty 
for  two  or  three  years,  and  good  results  are  sometimes 
obtained  from  seeds  eight  to  ten  years  old  if  they  have 
been  kept  dry.  But  exposure  to  cold  and  moisture,  or 
frequent  changes  in  moisture  content,  may  render  them 
incapable  of  germination  the  year  following  maturity. 
Seeds,  too  old  to  grow  under  ordinary  conditions  preva- 
lent in  the  field,  may  often  be  made  to  germinate  under 
optimum  conditions  of  moisture  and  temperature. 

There  are  no  authentic  cases  on  record  of  the  germina- 
tion of  seeds  of  maize  more  than  ten  or  twelve  years  old, 
and  twenty-five  years  might  reasonably  be  set  as  the 
maximum  period  of  viability.  Newspaper  stories  of 
the  germination  of  seeds  of  maize  that  have  been  dug 
from  Indian  mounds  are  to  be  regarded  as  examples 
of  sensational  journalism. 

Near  the  end  of  the  term  of  viability,  the  final  indica- 
tion of  life  takes  the  form  of  abnormal  germination,  due  to 
the  inability  of  the  plumule  or  of  the  root  to  rupture  the 
pericarp.  Sometimes  both  fail,  and  only  a  secondary 
root  appears.  At  times,  secondary  roots,  unable  to 
break  out  of  the  pericarp,  may  grow  to  a  considerable 
length,  winding  themselves  around  the  contents  of  the 
seed.  This  is  especially  likely  to  happen  when  immature 
seeds  germinate  on  the  cob  while  yet  inside  the  husk. 
These  abnormally  emerging  plants  are  unable  either  to 
secure  moisture  or  to  make  food,  and  soon  die.  Thus, 
seed  germination  is  seen  to  be  complicated  by  the  fact 
that  the  seed  is  never  normally  free  from  the  rest  of  the 
fruit. 


STRUCTURE  AND  GERMINATION  OF  THE  SEED  35 


Germination. — When  a  viable  grain  of  corn  is  sur- 
rounded with  proper  conditions  of  moisture,  temperature, 
and  air,  germination  proceeds  by  an  orderly  succession 
of  definite  steps.  The  whole  fruit  imbibes  water  and 
swells,  the  increase  in  weight  often  being  as  much  as 
100  per  cent.  In  thirty-six  to  sixty  hours,  the  primary 
root  bursts  the  pericarp,  breaks  out  of  the  coleorhiza, 
and  makes  its  way  downward 
(Figs.  20-23).  ^  f^w  hours  later, 
two  or  more  secondary  roots 
make  their  appearance  from  the 
node  to  which  the  cotyledon  is 
attached.  Because  of  structural 
peculiarities,  these  are  directed 
upward  at  first,  but  after  their 
emergence  they  respond  to 
gravity  and  start  downward. 
While  the  secondary  roots  are  de- 
veloping, the  enlarging  plumule 
also  breaks  through  the  pericarp  and  starts  upward. 
The  coleoptile  remains  intact,  however,  until  growth 
has  brought  its  tip  to  the  surface  of  the  soil.  This 
plumule  sheath  is  of  great  importance  to  the  plant  in 
furnishing  a  protection  for  the  tender  foliage  leaves  and 
providing  a  sharp  spike  to  open  the  way  through  the  soil. 

Before  the  rupture  of  the  coleoptile,'  it  and  the 
plumule  usually  increase  ten  to  twenty  times  their 
original  length,  but  the  greater  part  of  the  elongation 
responsible  for  bringing  the  leaves  above  the  surface 

'  The  exact  structure  of  the  parts  of  the  embryo  here  discussed  is  a 
point  still  in  controversy,  but  this  interpretation  seems  to  have  the  weight 
of  evidence  on  its  side.  For  a  summary  of  the  arguments  on  various 
phases  of  this  question  see  the  writer's  paper  (158). 


Figs. 


23. — Steps    in 


the  germination  of  a  grain 
of  corn. 


36 


THE  STORY  OF  THE  JMAIZE  PLANT 


is  in  the  internode  of  the  epicotyl  immediately  below 
the  coleoptile. 

The  depth  to  which  a  grain  of  corn  may  be  planted, 
with  fair  promise  of  successful  germination,  depends 
upon  the  ability  of  this  internode  to  elongate.  If  the 
seed  is  planted  so  deep  that  the  foliage  leaves  break 
out  of  the  coleoptile  before 
reaching  the  surface  of  the 
soil,  the  plant  usually  dies, 
or  is  much  retarded  in  its 
development.  The  same 
fate  befalls  it,  even  when 
the  seed  has  been  planted 
at  less  depth,  if  growing 
conditions  are  so  unfavor- 
able that  the  energy  stored  in 
the  seed  cannot  be  used 
economically  in  germination. 
For  this  reason,  corn  may  be 
planted  deep  when  the  soil  is 
warm  and  comparatively  dry, 
but  must  be  planted  at  less 
depth  when  the  soil  is  cold 
and  wet.'  The  seeds  of  some 
varieties  are  so  weak  that  an 
inch  is  the  maximum  depth  to  which  they  may  be  planted 
under  the  most  favorable  conditions;  but  the  Indians  of 
the  arid  regions  of  the  southwestern  parts  of  the  United 
States  have  varieties  that  can  be  planted  i8  inches  deep.^ 

•  The  differences  in  the  proportions  of  parts  of  the  plant,  due  to  deep 
and  to  shallow  planting,  are  shown  in  Figs.  24  and  25. 

2  Collins  (27). 


Figs.  24,  25. — Effects  of  deep 
and  shallow  planting.  S,  cole- 
optUe  (plumule  sheath).  The  one 
gram  was  planted  5  inches  deep; 
the  other  was  barely  covered. 


STRUCTURE  AND  GERMINATION  OF  THE  SEED     37 


As  this  elongated  internode  of  the  epicotyl  reaches 
its  ultimate  length,  roots  spring  from  the  node  above  it. 
These,  with  others  arising  from  the  higher  nodes,  are 


Figs.  26,  27. — Fig.  26,  seedling  at  the  end  of  germination.  Fig.  27, 
longitudinal  section  of  germinating  grain,  showing  at  E  the  region  in  which 
the  endosperm  is  being  digested  by  enzymes  secreted  by  the  cotyledon. 

destined  finally  to  become  the  main  part  of  the  root 
system  of  the  plant.  The  primary  root,  and  the  roots 
arising  from  the  first  node  of  the  seedling,  serve  their 
function  chiefly  during  germination. 

Because  of  its  double  vascular  system,  the  ruptured 
coleoptile  is  often  split  into  two  lobes  at  the  top.     This 


^S  THE  STORY  OF  THE  MAIZE  PLANT 

has  been  taken  to  indicate  that  the  coleoptile  is  the 
homologue  of  the  ligule  of  the  vegetative  leaf,  inasmuch 
as  the  ligules  of  many  grasses  have  a  bifid  apex.'  But 
this  theory  has  generally  been  abandoned  in  favor  of 
the  idea  that  the  coleoptile  is  a  modified  fohage  leaf. 

Meanwhile,  the  cotyledon  has  been  absorbing  the 
endosperm  and  transferring  it  into  the  growing  tissues 
of  the  seedling  (Fig.  27,  p.  37).  The  surface  of  the 
scutellum  next  to  the  endosperm  contains  glandular  cells 
which  produce  the  enzymes  that  digest  the  endosperm. 

When  the  roots  of  the  seedling  have  established 
connection  with  a  permanent  supply  of  moisture,  and 
the  foliage  leaves  are  expanded  and  ready  to  begin 
their  functions,  germination  may  be  said  to  be  finished 
(Fig.  26.)  At  about  this  time,  or  a  little  later,  the  last 
of  the  food  stored  in  the  endosperm  is  consumed,  and 
the  new  plant  begins  its  independent  existence. 

'Worsdelldr-'). 


CHAPTER  VI 
ANATOMY  AND  PHYSIOLOGY  OF  THE  STEM 

In  the  structure  of  its  vegetative  parts,  the  maize 
plant  is  very  similar  to  the  other  grasses;  and  the 
grasses,  as  a  group,  are  characterized  by  only  relatively 
slight  modifications  of  the  fundamentals  common  to 
all  the  higher  flowering  plants. 

The  individual  plant  consists  of  two  well-defined 
parts:  the  roots  and  the  aerial  shoot.  The  latter  is 
made  up  of  the  stem  and  the  leaves.  The  roots  hold 
the  plant  in  position  and  obtain  water  and  minerals 
from  the  soil;  the  leaves  are  chiefly  responsible  for  the 
elimination  of  water  and  for  the  synthesis  of  organic 
food  materials.  The  stem  supports  the  leaves  and 
flowers  and  affords  a  line  of  transportation  between 
leaf  and  root. 

At  a  definite  time  in  the  life-cycle,  the  staminate 
inflorescence  appears  as  the  metamorphosed  terminal 
portion  of  the  main  shoot,  and  it  is  soon  followed  by 
one  or  more  pistillate  inflorescences  terminating  lateral 
branches.  The  pistillate  inflorescence  becomes  in  time 
the  mature  ear.  The  basal  branches  of  the  plant, 
usually  known  as  tillers  or  suckers^  have  structurally 
the  same  origin  as  the  ear-bearing  branches,  but  they 
early  take  root  and  make  varied  development.  Some 
grow  as  tall  as  the  main  stem  and  resemble  it  in  all 
details;  at  other  times,  they  become  nothing  more  than 
short  vegetative  shoots;  and  between  these  two  ex- 
tremes various  gradations  occur.     The  variable  inflores- 


40  THE  STORY  OF  THE  MAIZE  PLANT 

cence  of  the  suckers  is  significant  and  will  be  described 
later.' 

The  unit  of  structure. — The  stem  is  marked  into 
definite  segments  by  the  occurrence  of  nodes,  at  each 
of  which  is  attached  a  leaf  and,  in  most  instances,  a  bud 
or  a  branch.  An  interaode,  together  with  the  leaf  at 
its  upper  end.  and  the  bud  at  its  lower  end,  consti- 
tutes a  phytomer.  the  unit  of  structure  of  the  shoot 
(Fig.  34V 

Any  single  phytomer  shows  the  fundamental  anatom- 
ical characteristics  of  the  whole  vegetative  shoot. 
The  upper  intemodes  are  straight  and  nearly  cylindrical. 
The  buds  at  the  upper  nodes  are  small  and  poorly 
developed,  or  sometimes  represented  by  only  a  meriste- 
matic  region.  The  intemode  immediately  above  each 
ear  is  deeply  grooved  on  one  side  and  bent  concave  to 
the  ear.  The  intemodes  below  the  ear  are  straight,  but 
often  flattened;  a  groove  on  one  side  of  each  of  these 
contains  the  bud.  These  grooves  are  alternately  arranged 
on  succeeding  intemodes,  corresponding  to  the  alternate 
arrangement  of  the  leaves  and  buds. 

Minute  anatomy. — The  arrangement  of  the  tissues  in 
the  t\-pical  grass  stem  is  favorable  to  the  development 
of  great  length  and  rigidity,  combined  with  lightness 
and  small  girth ;  but  the  maize  plant  is  far  less  successful 
than  many  other  grasses  in  attaining  extreme  proportions 
in  the  dimensions  of  its  stem.  It  has  a  relatively  thick, 
hea^y  stem,  made  hea\"ier  by  its  content  of  a  soHd  pith, 
a  characteristic  which  it  shares  with  few  other  grasses. 

The  epidermis  of  the  stem  is  much  like  that  of  the 
leaf.     It  is  made  up  of  rectangular  cells,  whose  walls, 

'  See  chap.  xiv. 


ANATOMY  AXD  PHA'SIOLOGY  OF  THE  STEM      41 

unlike  those  of  the  foliar  epidermis,  are  hardened  vrith. 
deposits  of  silica.  The  stomata  are  sirmlar  to  those  of 
the  leaf. 

Inclosing  the  other  parts  of  the  culm  is  a  thick, 
hard  shell  composed  of  the  silicified  epidermis  and  a 
layer  of   sclerenchyma.     The  pith   is   traversed    longi- 


FiG.  2S. — Cross-section  of  an  intemode  of  t±ie  stem 

tudinally  by  numerous  vascular  bundles,  which  sen-e  as 
avenues  of  transportation  and  as  tensUe  reinforcement, 
the  latter  function  being  correlated  with  their  tendency 
toward  a  peripheral  distribution  (Fig.  2S). 

At  the  nodes,  the  pith  is  usually  more  compact, 
and  the  vascular  tissue  less  regular  than  in  the  inter- 
nodes.     Some  of  the  bundles  pass  directly  from  one 


42 


THE  STORY  OF  THE  MAIZE  PLANT 


internode  into  the  next,  and  some  are  diverted  into  the 
leaf  and  bud;  but  many  of  them  anastomose,  or  show 
other  irregularities. 


Fig.  29. — Section  of  a  well-developed,  centrally  located  vascular 
bundle.  S,  sclerenchyma;  Pph,  protophloem;  Ph,  phloem;  T,  trachea 
of  the  xylem;   X,  tracheids;   Px,  protoxylem;  P,  parenchyma. 

The  vascular  bundle. — In  a  transverse  section  of  a 
mature  and  well-formed  vascular  bundle  (Fig.  29),  the 
most   prominent   feature   is   a   pair  of   large   tracheae. 


ANATOMY  AND  PHYSIOLOGY  OF  THE  STEM      43 

Connecting  these  is  a  group  of  xylem  elements,  and  at 
one  side  of  the  latter  is  a  large  air  space  containing  one 
or  more  spiral  or  annular  vessels.  On  the  other  side  of 
the  xylem  is  the  phloem,  made  up  of  large  sieve  tubes 

St 


Fig.  30. — A  vascular  bundle  near  the  periphery  of  the  stem.  E,  epi- 
dermis; Si,  stoma;  P,  parenchyma;  Ph,  phloem;  T,  trachea;  S, 
sclerenchyma;  P,  pith. 


and  small  companion  cells,  all  more  or  less  regularly 
arranged.  In  the  arrangement  of  all  the  bundles  there 
is  a  tendency  for  the  phloem  to  be  turned  toward  the 
outside  and  the  xylem  toward  the  inside  of  the  stem,  but 
this  tendency  is  less  evident  near  the  center  than  toward 


44 


THE  STORY  OF  THE  IMAIZE  PLANT 


the  periphery.  The  vascular  bundles  are  surrounded  by 
sheaths  of  sclerenchyma,  whose  cells  are  fairly  uniform 
except  in  the  neighborhood  of  the  oldest  part  of  the 
phloem,  where  they  are  often  much  enlarged.  This 
sheath  is  responsible  for  the  fibrous  nature  of  the  vascular 
bundle. 

Development  of  the  stem. — The  formative  period  of 
development  in  the  main  shoot  of  the  corn  plant  is  of 


Figs.  31,  32. — Fig.  31,  a  vascular  bundle  very  much  metamorphosed. 
£,  epidermis;  P,  parenchyma;  5,  sclerenchyma;  P//,  phloem;  P,  trachea. 
Fig.  32,  a  vascular  bundle  represented  by  only  a  strand  of  sclerenchyma. 

short  duration.  In  an  ordinary  seedHng,  5  to  10  inches 
tall,  all  the  phytomers  and  the  main  branches  of  the 
terminal  inflorescence  have  often  been  formed.  The 
first  few  phytomers  reach  maturity  without  any  consider- 
able increase  in  length  of  thickness,  the  number  of  these 
varying  with  growing  conditions  and  depth  of  planting. 
But  the  size  of  the  succeeding  mature  units  is  quickly 
increased  until  a  maximum  diameter  is  reached  in  the 
first  or  second  internode  wholly  above  the  ground. 
Above  this  the  succeeding  mature  internodes  are  thinner 


ANATOMY  AND  PHYSIOLOGY  OF  THE  STEM      45 


and  longer.  The  result  is  a  stem  tapering  gradually 
toward  the  tassel  and  abruptly  downward  to  the  coty- 
ledonary  node  (Fig.  ss)- 
A  young  internode  is 
capable  of  increasing  in  both 
length  and  thickness  for  a 
time,  but  growth  in  both 
directions  soon  reaches  a 
limit.  Increase  in  thickness 
is  accompanied  by  an  in- 
crease in  the  number  rather 
than  the  size  of  the  vascu- 
lar bundles.  A  new  bundle 
arises  as  a  longitudinal 
strand  of  procambium  in 
the  parenchyma  of  the  young 
stem,  and  a  protophloem  and 
protoxylem  are  soon  formed. 
These  temporary  forerun- 
ners of  the  permanent  vas- 
cular elements  are  of  great 
importance  while  the  stem 
is  elongating;  but,  as  the  ulti- 
mate length  of  any  part  of 
the  internode  is  reached,  the 
permanent  xylem  and  phloem 
in  that  part  are  laid  down  and 
matured.  The  meristematic 
tissue  present  between  the 
xylem  and  phloem,  in  early 
stages  of  development,  functions  as  such  for  only  a  short 
time;  its  cells  soon  cease  to  divide,  and  mature  as  xylem 


Fig.  33. — A  diagrammatic  lon- 
gitudinal section  of  a  young  maize 
plant,  showing  regions  of  develop- 
ment. The  density  of  shading 
shows  relative  potentiality  for 
further  development.  T,  terminal 
bud;  £,  lateral  bud  (ear);  i?,  but- 
tress root;  C,  cotyledon;  consecu- 
tive nodes,  beginning  with  the 
lowest,  are  indicated  Ni,  N2,  etc. 


46  THE  STORY  OF  THE  MAIZE  PLANT 

and  phloem.  This  is  responsible  for  the  uniformly  limited 
size  of  the  vascular  bundles.  In  the  mature  bundle,  the 
protophloem  remains  as  a  thin  layer  of  disintegrated 
cells  between  the  phloem  and  the  bundle  sheath;  the 
annular  and  spiral  vessels  are  the  remnants  of  the 
protoxylem  (Fig.  29). 

Elongation  of  the  internode  continues  long  after  the 
ultimate  diameter  has  been  reached.  In  any  internode, 
the  oldest  part  is  at  the  upper,  and  the  youngest  part 
at  the  lower  end;  and  a  region  of  embryonic  tissue  in 
the  latter  position  is  responsible  for  increase  in  length. 
This  segment  of  growing  tissue  above  each  node  would 
constitute  a  weak  place  in  the  stem  were  it  not  for  the 
support  provided  by  the  surrounding  leaf  sheath.  Even 
after  all  normal  increase  in  length  has  ceased,  this 
meristematic  region  is  still  present,  and  may  resume 
activity  if  the  stem  be  placed  in  a  horizontal  position. 
Under  such  conditions,  the  internode  begins  to  elongate 
on  the  lower  side,  doing  its  individual  part  in  an  attempt 
to  bring  at  least  the  terminal  portion  of  the  stem  into  a 
vertical  position. 


CHAPTER  VII 

STRUCTURE  AND  FUNCTIONS  OF  THE  LEAF 

The  leaf  consists  of  three  distinct  parts:  the  sheath, 
which  surrounds  and  strengthens  the  meristematic  part 
of  the  next  higher  internode;  the  blade,  or  lamina, 
leaving  the  stem  near  the  node  next  above  the  one  to 
which  it  is  attached;  and  the  collar-like  ligule,  attached 


Figs.  34,  35. — Fig.  34,  parts  of  the  leaf.  B,  blade;  iV,  node;  L, 
ligule;  S,  sheath;  A,  auricle.  Fig.  35,  the  leaf  of  Arundinaria,  one  of 
the  Bamboos,  for  comparison  with  that  of  maize.  5,  blade;  P,  petiole; 
L,  ligule;  S,  sheath. 

at  the  top  of  the  sheath  and  closely  surrounding  the 
stem.  The  base  of  the  lamina  is  extended  into  two 
auricles  (Fig.  34). 

The  phylogenetic  significance  of  the  leaf  of  the 
grasses,  and  the  homology  between  its  parts  and  those 


48  THE  STORY  OF  THE  MAIZE  PLANT 

of  the  leaves  of  other  plants,  have  afforded  opportunity 
for  much  speculation,  and  unanimity  of  opinion  does  not 
prevail.  The  lamina  is  doubtless  the  equivalent  of  the 
structure  elsewhere  having  the  same  name;  the  sheath 
is  probably  the  homologue  of  the  enlarged  leaf  base; 
and  the  ligule  seems  to  be  a  modified  pair  of  stipules.' 

The  blade  of  the  leaf  is  a  thin,  fiat,  ribbon-like 
structure,  tapering  slowly  from  an  auricled  base  to  an 
attenuate  tip.  Support  is  provided  by  a  firm  midrib 
extending  the  full  length.  This  is  merely  a  thickened 
portion  of  the  blade,  made  up  principally  of  pith  and 
sclerenchyma,  devoid  of  chlorophyll,  and  traversed  by 
numerous  vascular  bundles.  Parallel  to  the  midrib,  and 
spaced  at  regular  intervals,  are  numerous  smaller  veins, 
each  having  a  single  vascular  bundle.  These  vary  in 
size,  every  tenth  to  fiftieth  one  being  much  larger  than 
the  others.  They  seldom  anastomose  bodily,  but 
frequent  vascular  cross-connections  provide  for  lateral 
as  well  as  longitudinal  conduction.  Most  of  the  larger 
veins  may  be  traced  down  the  blade  to  the  sheath,  and 
down  it  to  the  node,  where  they  enter  the  stem. 

The  lamina  curves  away  from  the  stem  in  a  graceful 
arch,  and  its  wings  display  a  gently  undulating  fulness. 
These  structural  features,  with  the  abihty  of  the  sheath 
to  twist  slightly  on  the  culm,  give  to  the  leaf  an  elasticity 
that  does  much  to  save  it  from  injury  in  the  wind. 

Lobed  leaves. — As  the  young  leaf  develops  in  the  bud, 
there  is  a  time  when  the  two  edges  of  the  rolled  structure 
are  in  contact  with  each  other  long  enough  for  one  or 
both  to  receive  an  injury  sufficient  to  cause  the  develop- 

'  These  homologies  are  suggested  in  a  striking  way  in  the  bamboos, 
which  have  a  short  petiole  between  the  sheath  and  the  lamina  (Fig.  35). 


STRUCTURE  AND  FUNCTIONS  OF  THE  LEAF     49 

ment  of  a  lobe  on  the  mature  leaf.  Sometimes  the  leaf 
has  a  single  lobe,  but  quite  as  often  there  are  two. 
Consistent  with  their  early  origin,  these  lobes  do  not 
have  the  appearance  of  pieces  mechanically  split  off 
the  leaf,  but  their  edges  exhibit  the  marginal  modifica- 
tions of  the  epidermis  of  normal  parts  of  the  leaf. 

The  epidermis. — The  epidermis  of  the  leaf  is  made 
up  of  rectangular  cells  whose  walls  are  wrinkled  into 


Fig.  36. — Portion  of  the  epidermis  of  the  leaf.    S,  stoma;  G,  guard  cell 

minute,  undulating  irregularities  (Fig.  36).  The  stomata, 
which  are  arranged  in  parallel  longitudinal  rows,  are 
somewhat  more  numerous  in  the  lower  than  in  the  upper 
epidermis — about  60,000  to  100,000  occurring  in  a 
square  inch  of  the  former,  and  50,000  to  60,000  per 
square  inch  in  the  latter.  No  reliable  data  are  at  hand  as 
to  the  efficiency  of  the  stomata  in  regulating  transpiration. 
The  lower  epidermis  is  glabrous,  but  the  upper 
surface,  and  that  of  the  sheath,  may  range  from  glabrous 
to  velvety  pubescent.     The  pubescence  is  made  up  of 


5° 


THE  STORY  OF  THE  IMAIZE  PLANT 


minute,  soft,  unicellular  hairs,  each  of  which  is  a  modified 
epidermal  cell. 


M       H 


Fig.  37. — Diagram  of  a  cross-section  of  the  blade  of  the  leaf.  S, 
sclerenchyma;  P,  parenchyma;  B,  vascular  bundle;  M,  mesophyll; 
//,  hj-groscopic  cells  with  adjacent  hairs. 


Fig.  38. — Cross-section  of  blade  of  leaf.  H,  a  leaf  hair  (trichome) ;  He, 
hygroscopic  cell;  S,  stoma;  E,  epidermis;  M,  mesophyll;  5, vascular  bundle. 

Color. — The  midrib,  auricles,  ligule,  and  larger  veins 
are  yellowish  or  almost  colorless.  Other  parts  of  the 
leaf  show  various  tints  and  shades  of  green,  the  seat  of 
the  color  being  the  chloroplasts  in  the  cells  of  the  meso- 
phyll   (Fig.    38).     The   development   and   retention   of 


STRUCTURE  AND  FUNCTIONS  OF  THE  LEAF      51 


this  green  color  depends  upon  a  proper  environment. 
Plants  that  are  exposed  to  too  low  a  temperature,  or  to 
insufficient  light,  tend  to  lose  their  color;  and  the  same 
effect  may  be  produced  by  too  much  moisture  in  the 
soil,  or  by  the  presence  of  injurious  substances,  or  the 
lack  of  necessary  minerals,  notably  iron,  in  the  soil. 

Besides  these  effects  of  environment,  there  are 
certain  occurrences,  of  an  inherited  nature,  in  which 
the  plant  assumes  a 
similar  appearance. 
Certain  races  have  a 
recessive  hereditary 
factor  for  the  total  or 
partial  absence  of 
chlorophyll,  and  in- 
breeding brings  out 
albinos,  or  individuals 
with  a  reduced  amount 
of  chlorophyll.^  Other 
varieties  show  a  leaf 
variegation  in  the 
form  of  white,  red,  or 
yellow  stripes. 

Histology. — In  cross-section,  the  leaf  blade  and 
sheath  are  much  alike,  the  chief  difference  being  in  the 
thickness  and  relative  amount  of  chlorophyll-bearing 
tissue  (Figs.  37-39).  The  mesophyll  consists  of  loosely 
arranged  cells,  irregular  in  shape.  Beneath  each  stoma 
is  a  large  intercellular  air  space.  The  vascular  bundles 
are  similar  to  those  of  the  stem,  although  less  reg- 
ular in  size  and  shape.     The  smaller  bundles  have  a 

'  Lindstrom  (105)  and  Miles  (107). 


Fig.  39. — Section  of  the  leaf  through 
one  of  the  larger  vascular  bundles. 
Sc,  sclerenchymatous  bundle  sheath; 
E,  epidermis;  T,  trachea;  P,  phloem. 


52 


THE  STORY  OF  THE  MAIZE  PLANT 


'ittiaiXXli 


40 


sheath  whose  cells  are  filled  with  large  prominent 
chloroi)lasts/  Others,  especially  the  largest  ones,  are 
surrounded  by  heavy  sheaths  of  sclerenchyma,  which 
often  extend  to  the  epidermis  and  even  produce  prom- 
inent longitudinal  ridges  on  the  leaf  sheath. 

At  regular  inter- 
vals in  the  upper 
epidermis,  occur 
longitudinal  groups 
of  hygroscopic  cells. 
Under  ordinary  con- 
ditions, these  are 
gorged  with  water, 
but  when  conditions 
are  favorable  for 
excessive  transpira- 
tion, these  cells 
shrink  from  loss  of 
water  and  shorten 
Figs.  40,  41.— Fig.  40,  section  of  a  leaf  ^he  epidermis  on 
well  supplied  with  moisture.     Fig.  41,  section       ,  .,         , 

of  a  leaf  suffering  from  excessive  transpira-  ^^^  upper  Side,  ttie 
tion.  He,  the  hygroscopic  cells,  which  lose  Combined  effect  of 
moisture  and  shrink,  thus  shortening  the  shrinkage  in  many 
upper  epidermis.  ^^^^    ^^.^^p^    ^^j^^^ 

to  cause  the  leaf  to  rolt  up  (Figs.  40,41).  When  the 
leaf  is  rolled,  the  upper  epidermis,  and  usually  a  part 
of  the  lower,  is  protected  from  the  air.  This  behavior  is 
probably  quite  as  effective  as  the  opening  and  closing  of 
the  stomata  in  regulating  the  loss  of  moisture.     Since 

»  As  noted  by  Kiesselbach  (98,  p.  189),  the  appearance  of  these  cells 
in  preparations  stained  bj-  ordinary  methods  is  very  deceptive,  the 
chloroplasts  assuming  a  striking,  abnormal  arrangement. 


STRUCTURE  AND  FUNCTIONS  OF  THE  LEAF      53 

the  curving  blade  must  straighten  on  rolling,  the  leaves 
have  a  characteristic  erect  position  when  rolled. 

Most  of  the  minute  hairs  constituting  the  pubescence 
of  the  leaf  blade  are  arranged  along  these  hygroscopic 
areas  of  the  epidermis,  and  each  hair  curves  over  as  if 
to  protect  the  turgid  cells.  The  function  of  these  hairs 
is  problematical.  At  first  glance,  it  seems  plausible 
that  they  prevent  excessive  transpiration  by  protecting 
the  cells  that  lose  water  most  readily.  But,  if  they  have 
any  protective  function  in  this  way,  they  really  permit 
greater  transpiration  in  the  long  run,  for  it  is  through 
loss  of  water  from  the  tissue  that  these  hairs  seem  to 
protect  that  the  leaf  is  enabled  to  roll  up  and  protect 
itself  from  drying  conditions. 

The  ligule.- — ^The  ligule  is  a  membranous  outgrowth 
of  the  epidermis.  It  fits  collar  like  around  the  stem, 
and  its  chief  function  seems  to  be  to  prevent  the  entrance 
of  water  into  the  space  between  the  sheath  and  the 
culm.  One  or  more  varieties  of  corn  have  been  isolated 
by  inbreeding,  in  which  the  ligules  and  auricles  of  the 
leaves  are  lacking.^ 

Metabolism. — Chiefly  upon  the  leaf,  and  less  upon 
the  green  parts  of  the  stem,  rests  the  responsibility  of 
initiating  the  food-making  process  of  the  plant  by 
synthesizing  the  carbohydrates,  which  become  the  basis 
of  all  food.  From  the  air,  which  enters  through  the 
stomata  and  permeates  the  intercellular  spaces  of  the 
green  parts  of  the  leaf,  carbon  dioxide  is  taken,  and  the 
vascular  system  contributes  water,  which  has  been 
brought  up  from  the  soil.  These  oxides  meet  in  the 
chloroplasts,  which,  in  the  presence  of  sunlight  and  good 

•  Emerson  (53). 


54  THE  STORY  OF  THE  MAIZE  PLANT 

growing  conditions,  synthesizes  a  carbohydrate,  which 
is  temporarily  deposited  in  the  cell  in  the  form  of  starch. 
Oxygen  escapes  as  a  by-product. 

The  enz)rmes  of  the  cell  may  readily  change  the 
carbohydrate  from  one  form  into  another,  some  of 
these  forms  being  soluble  and  others  insoluble.  In  the 
soluble  form,  they  may  be  transported  through  the 
phloem  to  other  parts  of  the  plant  to  be  stored  or  used 
otherwise.  Carbohydrates  contain  all  the  materials 
necessary  for  the  formation  of  fats,  but  the  details  of 
the  process  by  which  this  conversion  is  accomplished 
are  unknown.  From  the  water  taken  up  from  the  soil, 
nitrates  and  other  mineral  compounds  are  selected  and 
added  to  the  carbohydrates  to  form  proteins;  but  the 
synthesis  of  proteins  also  involves  processes  still  wrapped 
in  obscurity. 

Transpiration. — In  exposing  its  delicate  mesophyll 
to  the  air  for  the  absorption  of  carbon  dioxide  and  the 
elimination  of  waste  materials,  the  plant  unavoidably 
brings  about  a  favorable  condition  for  the  loss  of  water 
by  evaporation.  This  loss  is  made  up  by  the  constant 
upward  movement  of  water  from  the  roots.  The  escape 
of  water  is  probably  not  so  effective  in  condensing 
dilute  solutions  of  mineral  salts  as  is  sometimes  supposed, 
the  concentration  of  these  being  kept  in  a  state  of 
equihbrium  by  osmosis.  Neither  does  this  evaporation 
of  water  seem  to  be  necessary  to  keep  the  plant  cool. 
Transpiration  is  rather  to  be  looked  upon  as  an  inadvert- 
ent necessity  than  as  the  performance  of  a  function. 
To  maintain  proper  relations  with  the  atmosphere,  the 
plant  must  pay  the  price  in  water.  When  that  price 
is  reasonable,  it  is  paid,  and  the  plant  flourishes;   when 


STRUCTURE  AND  FUNCTIONS  OF  THE  LEAF      55 

it  is  too  great,  the  plant  protests  by  closing  its  stomata 
and  rolling  its  leaves,  and  the  active  resumption  of 
normal  processes  awaits  better  conditions. 

Guttation. — ^The  pressure  exerted  by  the  various 
forces  responsible  for  the  upward  movement  of  water 
in  the  plant  often  forces  water  in  the  Kquid  form  from 
the  leaves  when  conditions  are  not  favorable  for  evapora- 
tion. This  process,  known  as  guttation,  explains  the 
common  occurrence  of  drops  of  water  on  the  leaves  of 
corn  or  other  plants  early  in  the  morning. 


CHAPTER  VIII 

BRANCHES  OF  THE  SHOOT 

Probably  every  node  of  the  corn  plant  bears  a  bud 
or  the  mcristematic  rudiment  of  one.  At  some  of  the 
upper  nodes,  these  rudiments  are  so  small  as  to  be  practi- 
cally indistinguishable  from  the  embryonic  tissue  of  the 
next  higher  internode,  and  many  of  the  buds  at  other 


Figs.  42-44. — Fig.  42,  a  highly  specialized  ear-bearing  branch. 
Fig.  43,  an  ear  with  leaf  blades  well  developed  on  its  husks.  Fig.  44,  an 
ear  showing  small  secondary  ears  resulting  from  the  development  of 
buds  in  the  axils  of  the  husks. 

nodes  make  such  limited  development  as  not  to  emerge 
from  the  leaf  sheath;  but  one  or  more  near  the  middle 
of  the  stem  develop  into  ear-bearing  branches,  and  those 
at  the  base  of  the  stem  often  develop  into  suckers. 

The  pistillate  6rjwc/z.— Vegetatively,  the  ear-bearing 
branch  is  much  like  the  main  shoot;  but  its  internodes  are 
56 


BRANCHES  OF  THE  SHOOT 


57 


so  much  contracted  in 
length  that  the  greatly 
enlarged  and  over- 
lapping leaf  sheaths 
form  the  well-known 
covering  of  husks 
(Fig.  42).  In  this 
branch,  the  uppermost 
internodes  are  short, 
and  the  lower  ones 
progressively  longer — 
a  condition  exactly 
opposite  that  prevail- 
ing in  the  main  culm 
(Fig.  45).  In  many 
instances,  the  husks 
bear  w  ell-developed 
laminae  and  ligules; 
but  these  structures 
are  usually  greatly 
reduced  or  entirely 
lacking  (Figs.  42,43). 
The  axis  of  this  shoot 
is  the  same  as  the 
main  stem  in  essen- 
tial structure,  but  its 

Fig.  45. — Diagram  of 
longitudinal  section  of  ear- 
bearing  branch.  S,  leaf 
sheath;  B,  axillary  bud,  an  undeveloped  ear-bearing  branch;  A'',  node 
of  the  main  axis;  S,  silks  exposed  beyond  the  ends  of  the  husks;  L,  ligule; 
B,\ea.l  blade;  H,  husk  of  the  ear,  a  greatly  enlarged  leaf  sheath;  C,  cob 
of  the  ear;  Eb,  secondary  ear  buds;  P,  prophyllum. 


58  THE  STORY  OF  THE  MAIZE  PLANT 

well-developed  vascular  tissue  and  the  close  proximity 
of  its  successive  nodes  give  to  its  interior  a  tangled, 
tough,  fibrous  nature. 


Figs.  46,  47. — Fig.  46,  a  many-eared  plant  of  one  of  the  "prolific" 
pop  varieties.     Fig.  47,  plant  with  basal  branches  (suckers). 

In  the  axil  of  each  husk  of  the  ear  is  borne  a  bud, 
and  some  of  these  occasionally  develop  into  small  branch 
ears  (Fig.  43).  These,  however,  must  not  be  confused 
with  the  branches  of  the  ear  of  branch  corn  (Fig.  84, 
p.  107)  nor  with  the  abnormal  branches  sometimes  found 
at  the  very  base  of  the  ear  above  the  uppermost  husk 


BRANCHES  OF  THE  SHOOT  59 

(Fig.  82,  p.  107).  These  latter  occurrences  are  branches 
of  the  inflorescence  proper  and  not  separate  axillary  in- 
florescences. 

Suckers. — The  suckers,  or  tillers,  at  the  base  of  the 
plant  (Fig.  4 7),. are  much  influenced  in  development  by 
nutrition,  moisture,  and  cultivation.  The  various  strains 
of  corn  also  have  distinctly  difi'erent  tendencies  as  to 
sucker  production.  In  structure,  these»  branches  range 
all  the  way  from  normal  ears  to  normal  shoots  having 
ears  and  tassels  of  their  own. 

The  prophyllum. — Adaxially  located  at  the  base  of 
every  branch  of  the  plant  is  a  structure  which,  in  the 
grasses,  has  received  a  limited  application  of  the  term 
"prophyllum."  Although  doubtless  the  first  leaf  of  the 
lateral  shoot,  and  usually  subtending  a  rudimentary 
bud,  the  prophyllum  has  a  distinctly  characteristic 
structure.  Its  lamina  and  ligule  are  usually  lacking,  and 
two  prominent  nerves  are  present.  The  latter  peculiar- 
ity is  probably  to  be  associated  with  the  crowded  quarters 
in  which  the  structure  develops.  The  palea  is  doubtless 
the  floral  homologue  of  the  prophyllum. 


CHAPTER  IX 


THE  ROOT  SYSTEM 

The  primary  root,  which  is  a  downward  continuation 
of  the  main  axis  of  the  embryonic  plant,  is  a  relatively 
unimportant  structure.  Very 
early  during  germination  its 
work  is  supplemented  by  that 
of  two  or  three  secondary  roots 
arising  from  the  first  node  of 
the  stem.  But  even  these  soon 
have  their  day,  and  during 
subsequent  development  the 
plant  depends  upon  roots  aris- 
ing from  still  higher  nodes. 
In  the  absence  of  any  device 
for  secondary  thickening,  none 
of  the  roots  ever  attain  any 
very  great  diameter,  and  the 
whole  root  system  is  essenti- 
ally fibrous.  Even  these  smal  I 
roots  may,  however,  penetrate 
the  soil  to  a  depth  of  as  much 
as  4  or  5  feet,  and  the  root 
system  may  radiate  from  the 
base  of  the  plant  for  a  distance 
of  5  or  6  feet. 

Tissues  of  the  root. — The  tip 
of  the  root  is  covered  with  a 
firm,  pointed  cap,  which  bears  the  brunt  of  forcing  a 

6o 


Figs.  48,  49. — Portions  of  a 
longitudinal  section  of  a  root  tip. 


THE  ROOT  SYSTEIVI 


6i 


way  through  the  soil  (Fig.  48).  This  hard  usage  keeps 
wearing  away  the  outer  part  of  the  cap,  but  is  continu- 
ally being  renewed  from  within. 

Immediately  back  of  the  cap,  in  the  tip  of  the  root 
proper,  is  a  region  of  meristematic  tissue,  which  is  the 
principal  seat  of  formation  of  new  cells  as  the  root  grows. 
In  still  older  regions  back  of  this,  the  plerome  and  peri- 
blem  are  differentiated,  and  in  due  time  the  cortex  and 
central  cyHnder  become 
well  defined.  When 
elongation  has  ceased, 
the   root   hairs   appear. 

The  central  cylinder 
contains  a  circle  of  large 
\-essels  alternating  with 
strands  of  phloem  (Figs. 
50-52).  Filling  all  parts 
of  the  cyhnder  not  oc- 
cupied by  the  vascular 
tissue,  is  a  soft  paren- 
chyma. The  endodermis 
is  readily  distinguished 
by  the  clear  outlines  and  thickened  radial  walls  of  its  cells. 

Root  hairs. — The  appearance  of  root  hairs  is  an 
incident  in  the  maturity  of  the  portion  of  the  root  on 
which  they  occur.  A  fully  developed  root  hair  (Fig.  53) 
is  a  cylindrical  elongation  of  a  single  epidermal  cell, 
rendered  more  or  less  irregular  by  the  pressure  of  part- 
icles of  soil  around  it.  Its  cytoplasm  is  mostly  disposed 
in  a  wall  layer,  in  which  the  nucleus  is  imbedded.  The 
middle  of  the  cell  is  a  large  vacuole,  whose  cell  sap  plays 
an  essential  role  in  the  functions  of  the  root  hair. 


Fig.  50. — Diagram  of  cross-section 
of  a  young  root.  H,  root  hair;  S,  scle- 
renchyma;  P, parenchyma;  PA, phloem; 
B,  a  branch  root;  E,  endodermis. 


62 


THE  STORY  OF  THE  MAIZE  PLANT 


As  the  root  grows  older,  the  root  hairs  lose  their  func- 
tion, the  epidermal  cells  die,  and  the  wearing  away  of 
the  outer  part  of  the  cortex  begins.     The  whole  root 


Figs,  s  i  ,  52. — Fig.  5 1 ,  portions  of  cross-section  of  a  young  root.  //,  root 
hair;  £,  epidermis;  P,  parenchyma;  P/;,  phloem;  T,  trachea.  Fig.  52, 
portions  of  cross-section  of  an  old  root.  H,  root  hair;  E,  epidermis; 
5,sclerenchyma;  P,parenchyma;  £»,endodermis;  P/t, phloem;  T,  trachea. 


THE  ROOT  SYSTEM 


63 


increases  in  thickness,  for  a  time,  by  the  growth  and 
multiphcation  of  its  cells,  but  no  cambium  appears,  as 
in  many  plants,  to  bring  about  a  continued  increase  in 
diameter. 

Osmosis  and  root  pressure. — The  function  of  the  root 
hair  is  to  extract  water  and  mineral  salts  from  the  soil 
and  to  eliminate  waste  products. 
These  activities  are  accomplished  by 
the  process  of  osmosis.  The  entrance 
and  exit  of  water  and  dissolved  sub- 
stances is  regulated  by  the  proto- 
plasmic membrane  of  the  root  hair. 
Its  effect  is  to  maintain,  inside 
the  cell,  a  characteristic  hydrostatic 
pressure  and  a  concentration  of 
solutes  which  is  the  optimum  under 
the  environmental  conditions.  Other 
epidermal  cells  of  the  root  perform 
the  same  functions  as  the  root  hairs, 
their  activity  being  limited  only  by 
the  amount  of  surface  exposed  to 
the  soil. 

The  water  taken  into  the  root  hair 
makes  its  way  to  adjoining  cells  of 
the  cortex,  where  there  is  less  turgor;  ^^^'  ^^'~^ 
and,  in  proceeding  from  cell  to  cell,  seeking  an  osmotic 
equilibrium,  it  reaches  the  vascular  tissue,  which  pro- 
ceeds to  distribute  it  to  all  parts  of  the  plant.  Some  of 
'^t  ultimately  reaches  the  mesophyll  of  the  leaves,  from 
which  it  tends  to  escape  into  the  air  by  transpiration. 
The  rate  of '  transpiration  and  guttation  largely  deter- 
mines the  amount  of  water  taken  in  by  the  root  hairs  in 


64 


THE  STORY  OF  THE  MAIZE  PLANT 


any  given  time.  The  ingress  of  minerals  is  regulated 
by  the  concentration  present  in  the  soil  water,  the 
concentration  permitted  within  the  cells  by  the  various 
osmotic  systems  concerned,  and  the  rate  at  which  sub- 
stances are  taken  out  of  solution  by  the  metabolic 
activities  of  the  plant. 

Secretion   and  excretion. — Some  of   the   products  of 
metabolism  make  their  way  out  of  the  root  by  way  of 

the  root  hairs.  Some  of 
these  may  be  regarded  as 
secretions,  inasmuch  as 
they  aid  in  the  decompo- 
sition of  the  soil;  but 
many  of  the  substances 
eliminated  by  the  roots 
ha^•e  no  known  functions 
and  are  often  toxic  in 
effect. 

Buttress  roots. — Coin- 
cident with  the  period  of 
rapid  elongation  of  the 
stem,  and  usually  before 
the  appearance  of  the 
tassel,  one  or  more  nodes  just  above  the  ground  may 
throw  out  whorls  of  large  spur  roots,  which  curve  out- 
ward and  downward,  tinally  entering  the  soil  and 
forming  a  timi  support  for  the  stem  (^Fig.  54).  These 
roots  are  much  thicker  and  stronger  than  those  produced 
underground;  their  sclerenchyma  is  well  developed,  and 
the  epidermis  is  silicilied ;  and  their  cortical  regions  often 
develop  chlorophyll  or  other  pigmentation.  Otherwise, 
they  resemble  the  ordinary  underground  roots.  e\'en  to 


Fig.  54. — Buttress  roots 


THE  ROOT  SYSTEM  65 

the  large  root  cap.  Different  strains  of  corn  and  differ- 
ent individual  plants  show  great  variation  in  the  pro- 
duction of  these  brace  roots.  In  some  varieties  they 
seldom  occur,  and  their  development  can  usually  be 
inhibited,  to  a  degree,  by  heaping  the  soil  about  the  plants 
during  cultivation.  In  other  varieties,  however,  and 
under  optimum  conditions,  these  roots  may  be  developed 
at  all  the  nodes  of  the  plant  up  to  2  or  3  feet  from  the 
ground.  They  usually  develop  on  the  lower  side  of  the 
stem  at  any  node  of  a  prostrate  plant. 


CHAPTER  X 

ECOLOGICAL  RELATIONS 

The  most  prominent  factor  in  the  ecological  relations 
of  maize  is  man.  What  man  calls  agriculture  is,  in  a 
large  measure,  the  making  of  an  environment  for  plants. 
Maize  agriculture  is,  and  has  been,  scarcely  more  than 
man's  attempt  to  shape  the  ecology  of  the  plant;  and 
the  result  is  a  plant  so  helpless  that  it  is  unable  any  longer 
to  perpetuate  itself  without  human  aid.  Modern  maize 
is  so  far  removed  from  the  conditions  that  surrounded  its 
wild  ancestor  that  little  is  known  of  its  natural  environ- 
ment in  early  times;  and  its  ecology  is  reduced  to  a 
problem  not  of  the  plant  but  of  man  who  acts  as  its 
agent. 

Distribution  .—yiaize  is  not  well  adapted  to  chance 
distribution  by  wind  or  water,  and  to  only  a  slight 
extent  by  animals.  It  was  no  series  of  chance  happen- 
ings, but  the  intent  of  man,  that  took  the  plant  from  the 
limited  region  of  its  nativity,  across  deserts,  mountains, 
and  oceans,  and  into  new  lands,  until  it  is  known  today 
throughout  the  civilized  world. 

Climate. — In  every  expression  of  its  choice  of  climatic 
conditions,  maize  points  to  its  origin  in  the  highlands  of 
the  tropics.  Bright  sunshine,  clear  air,  warm  days  and 
nights,  abundant  rainfall,  and  good  drainage  are  all  con- 
ducive to  its  welfare;  and  one  of  the  most  unfavorable 
conditions  that  can  be  visited  upon  the  plant  is  to  compel 
it  to  stand  through  cold,  cloudy  weather  with  its  roots 
in  a  water-soaked  soil. 

66 


ECOLOGICAL  RELATIONS  67 

The  seed  retains  its  vitality  best  if  kept  dry  and  warm 
from  maturity  until  planting  time,  very  cold  weather  or 
fluctuating  humidity  being  very  injurious.  Its  extreme 
sensitiveness,  in  these  respects,  may  have  been  acquired 
in  the  dry  seasons  of  its  native  home. 

Freezing  temperatures,  continued  for  any  considerable 
time  during  the  growing  season,  constitute  an  absolute 
Hmit  to  the  plant's  existence.  Seedlings  of  many  varie- 
ties are  able  to  stand  a  sharp  frost  or  two,  and  may  even 
recover  after  most  of  the  leaves  have  been  killed,  but 
as  much  as  a  day's  exposure  to  temperatures  below  freez- 
ing is  fatal.  The  agricultural  conquest  of  the  colder 
latitudes  by  maize  has  been  accomplished  both  by  a 
shortening  of  the  growing  season  and  by  the  develop- 
ment of  a  hardiness  to  withstand  temperatures  near  the 
freezing-point.  But  these  advantages  have  been  gained 
at  a  sacrifice  of  the  size  of  the  individual. 

The  successful  growing  of  corn  requires  a  season  of 
from  90  to  a  150  days  without  a  killing  frost.  The 
varieties  grown  in  any  locality  are  usually  adjusted 
to  the  length  of  the  growing  season,  it  being  of  advan- 
tage to  use  the  largest  variety  that  will  mature  in 
the  season  afforded.  Some  Canadian  varieties  will 
mature  in  two  months  from  the  time  of  planting,  and 
some  accounts,  not  well  substantiated,  report  varieties 
that  will  mature  in  six  weeks,  or  in  extreme  cases  in  a 
month.  On  the  other  hand,  some  of  the  large  vari- 
eties of  the  tropics  require  a  season  of  nine  to  eleven 
months. 

It  has  long  been  observed  that  varieties  taken  into 
colder  latitudes  tend  to  shorten  their  growing  season  and 
become  adapted  in  a  few  generations,  and  those  taken 


68  THE  STORY  OF  THE  MAIZE  PLANT 

into  regions  having  a  longer  summer  may  lengthen  their 
growing  season.  The  effects  of  selection,  conscious  or 
otherwise,  is  probably  sufficient  to  explain  this  behavior, 
in  view  of  the  extreme  heterozygosis  shown  by  ordinary 
varieties  of  maize.  The  fact  that  two  plantings  of  corn, 
made  a  month  apart,  may  come  to  maturity  almost 
simultaneously  in  the  fall  may  be  explained  by  the 
definitely  established  fact  that,  in  many  plants,  a  gradu- 
ally shortening  day  tends  to  hasten  sexual  maturity — 
this  influence  being  more  marked  in  the  higher  latitudes 
than  in  the  tropics,  and  in  later  parts  of  the  growing 
season  than  in  the  earlier. 

One  of  the  most  serious  conditions  that  has  to  be 
met  in  the  whole  life-cycle  of  the  plant  is  the  drought 
that  often  comes  about  tasseling  time,  or  a  little  earlier 
in  many  corn-growing  countries.  If  the  soil  is  moist 
enough  to  cause  the  seed  to  germinate  and  to  get  the 
roots  well  established,  and  if  cultivation  is  thorough, 
dry  weather  seldom  has  any  harmful  effects  before  the 
tassels  appear.  But  with  the  appearance  of  the  tassels 
and  the  elongation  of  the  stem,  there  is  a  great  increase 
in  transpiring  surface,  and  the  roots  are  often  unable  to 
supply  moisture  fast  enough  to  compensate  for  that 
given  off  in  transpiration. 

The  first  marked  indication  of  this  lack  of  moisture 
is  the  rolling  of  the  leaves.  This  is  a  normal  protective 
measure,  not  in  itself  of  any  serious  significance,  unless 
continued  for  several  days  in  succession;  but  when 
portions  of  the  upper  leaves  turn  white  and  begin  to  die, 
or  when  the  lower  leaves  dry  up,  the  injury  has  been 
serious.  The  hot  winds  that  often  sweep  over  level 
sections  far  inland  may,  in  a  single  day,  do  serious 


ECOLOGICAL  RELATIONS  69 

injury,  even  though  there  be  no  actual  deficiency  of 
moisture  in  the  soil. 

Wind  and  hail  often  damage  the  plant  mechanically 
by  blowing  down  or  breaking  off  the  stem,  or  by  tearing 
the  leaves.  A  plant  that  is  broken  off  or  blown  prostrate 
is  usually  a  total  loss;  if  merely  bent  or  loosened  in  the 
soil,  it  may  straighten  enough  to  complete  its  develop- 
ment. The  extent  of  the  damage  depends  largely  also 
upon  the  age  of  the  plant  affected.  Injury  of  this  kind 
seldom  comes  before  the  tassels  appear;  if  it  occurs  at 
the  time  of  pollination,  the  chances  for  anything  like  a 
normal  continuation  of  development  are  slight;  if  it 
follows  the  ''roasting  ear"  stage,  the  ear  may  mature 
but  there  is  a  greater  chance  of  decay. 

Only  a  very  severe  wind  can  do  any  appreciable 
injury  by  tearing  the  leaves,  and,  in  such  cases,  the 
damage  done  is  negligible  as  compared  with  that  suffered 
by  the  stems.  But  the  severe  local  hailstorms  of  early 
summer  often  riddle  the  plants,  sometimes  even  beating 
down  the  stems  as  well  as  the  leaves. 

Pollination. — The  transfer  of  pollen  from  the  stamen 
to  the  stigma  is  free  from  any  complications  with  birds 
or  insects,  but  its  accomplishment  is  fundamentally 
dependent  upon  certain  physical  and  climatic  conditions 
and  upon  the  proximity  of  other  maize  plants. 

Gravity  alone  will  accomplish  pollination,  but  if  no 
other  influence  were  brought  to  bear,  self-pollination 
would  prevail.  The  slightest  breeze,  however,  will  waft 
the  falhng  dust  to  the  stigmas  of  other  plants,  and  this  pos- 
sibly is  of  great  moment  to  the  species.  Since  the  plant 
is  monoecious,  its  gregarious  habit  and  the  advantages 
of  cross-polHnation  are  doubtless  intimately  associated. 


70  THE  STORY  OF  THE  MAIZE  PLANT 

The  successful  culmination  of  the  series  of  events 
immediately  following  pollination  is  dependent  upon  a 
warm,  humid  atmosphere  for  a  few  hours  at  least. 
Otherwise,  the  pollen  tube  grows  slowly,  or  is  subject 
to  a  fatal  degree  of  desiccation. 

Weeds. — Centuries  of  cultivation  have  rendered  the 
maize  plant  intolerant  of  the  proximity  of  other  plants 
which  shade  it  or  enter  into  competition  with  it  for  mois- 
ture. This  makes  it  impossible  to  grow  corn  under  trees 
and  imperative  that  weeds  be  kept  down,  especially 
when  the  plants  are  young.  An  undergrowth  of  other 
plants  later  in  the  season  is  less  injurious,  as  is  shown  by 
the  successful  practice  of  underplanting  with  beans, 
cowpeas,  or  pumpkins.  When  these  are  making  their 
greatest  growth,  their  interests  are  sufiEiciently  different 
from  those  of  the  corn  plants  at  that  time  to  obviate 
serious  competition. 

Each  locality  has  its  own  list  of  most  troublesome 
weeds,  and  little  may  be  said  without  going  into  detail. 
Throughout  the  Com  Belt,  the  weeds  usually  causing 
most  trouble  are  cockleburs,  morning-glories,  various 
species  of  Convolvulus,  twining  milkweeds,  ragweeds, 
smartweeds,  and  various  grasses. 

Birds  and  small  animals. — Since  maize  is  dependent 
upon  man  for  its  perpetuation  and  distribution,  most 
animals  stand  in  a  detrimental  relation.  The  character- 
istics that  make  the  plant  useful  to  man  also  subject  it  to 
the  depredations  of  birds,  mammals,  and  insects. 

The  deer  and  other  gramnivorous  mammals  that 
raided  the  cornfields  in  earlier  days  have  retreated  before 
the  increasing  population,  but  woodchucks,  muskrats, 
squirrels,  and  rabbits  have  survived  the  development  of 


ECOLOGICAL  RELATIONS  71 

the  principal  corn-growing  regions  of  this  country,  and 
remain  to  do  more  or  less  damage  to  the  crop  in  the 
field.  Mice  and  rats  are  the  cause  of  considerable 
damage  to  the  grain  in  storage. 

Crows,  blackbirds,  English  sparrows,  and  other  birds 
often  destory  the  seedlings  and  feed  upon  the  ears  as 
they  near  maturity.  Their  damage,  like  that  done  by 
squirrels,  is  not  so  much  in  the  amount  of  grain  eaten  as 
in  that  exposed  to  decay  in  the  ears  torn  open. 

In  countries  where  corn  has  recently  been  taken,  the 
birds  and  mammals  that  are  destructive  to  maize  are  for 
the  most  part  representatives  of  the  local  fauna  which 
have  adopted  the  plant  after  its  introduction.  A  few 
cosmopolitan  species,  like  mice,  rats,  and  the  English 
sparrow,  have  become  as  widespread  as  maize  itself 
through  their  habit  of  following  man  in  his  migrations. 

Insects. — The  insects  present  a  more  serious  problem 
than  that  offered  by  birds  and  mammals.  The  latter 
use  maize  as  a  supplement  to  a  variety  of  other  foods 
and  may  leave  it  unmolested  if  other  food  is  plentiful; 
but  many  of  the  insects  have  followed  maize  in  its  migra- 
tions and  have  become  so  thoroughly  adapted  to  it 
that  they  depend  upon  it  to  a  much  greater  extent.  It 
has  probably  more  insect  pests  than  any  other  cereal 
crop.  The  insect  population  is  so  numerous  that  attack 
upon  the  individual  is  futile,  and  the  intimate  relation 
between  pest  and  host  often  renders  mass  attack  hopeless. 

Wireworms  and  white  grubs'  are  destructive  during 
the  cool,  wet  weather  of  early  spring  because  of  their 

'  Wireworms  are  the  larvae  of  click  beetles  (Elateridae).  The 
common  white  grubs  are  the  larvae  of  various  species  of  the  May  beetle 
(Lachnosterna) . 


72  THE  STORY  OF  THE  MAIZE  PLANT 

habit  of  feeding  on  the  roots  and  the  germinating  seed. 
Several  species  of  cutworm'  also  attack  the  plant  as 
soon  as  its  leaves  appear  above  the  ground.  Their 
activity  usually  terminates  with  the  coming  of  warm 
weather. 

A  particularly  harmful  group  of  insects  in  all  corn- 
growing  countries,  especially  those  favored  by  mild 
winters,  includes  the  various  rootworms  and  bud  worms. 
These  are  the  larvae  of  beetles  and  moths.  They  usually 
enter  the  base  of  the  young  plant  and  feed  on  the  tender 
internal  parts.  If  the  terminal  bud  is  destroyed,  the 
clump  of  lateral  suckers  that  springs  up  gives  promise  of 
recovery,  but  the  abnormal  nature  of  the  growth  soon 
becomes  apparent.  If  the  bud  escapes  destruction,  the 
efifect  of  the  insect's  work  may  be  seen  in  the  perforations 
that  the  leaves  carry  to  maturity.  The  stalk  borer, 
which  is  the  larva  of  a  moth,  makes  its  way  into  the  base 
of  the  stem  and  upward  through  the  pith,  often  emerging 
near  the  ear.  Its  principal  effects  are  to  stunt  the  plant 
and  weaken  the  stem. 

The  billbug  is  a  weevil  common  to  warm  countries. 
It  pierces  the  stem  of  the  young  plant  and  burrows  about 
in  the  soft  tissue,  finally  laying  its  eggs  and  leaving  the 
larv^ae  to  sap  the  strength  of  the  plant. 

In  early  summer,  when  wheat  and  other  winter 
annual  grasses  have  matured  and  are  unfit  for  its  food, 
the  chinch  bug^  often  transfers  its  attack  to  maize.  The 
eggs  are  laid  on  the  plant  and  the  young  bugs  sap  its 
vitality  by  sucking  the  juice  from  the  tender  growing 
parts. 

'  The  larvae  of  several  species  of  moth. 
^  Blissiis  leucoptcris  Say. 


ECOLOGICAL  RELATIONS  73 

Both  the  roots  and  the  shoot  of  the  plant  are  often 
attacked  by  aphids.'  The  ants  that  are  often  so  numer- 
ous on  the  maize  plants  and  in  the  soil  about  the  roots 
are  probably  not  so  injurious  as  are  the  aphids  which  the 
ants  keep  in  domestication  for  their  honeydew. 

Many  kinds  of  caterpillars  feed  on  the  leaves  of  maize, 
but  little  harm  seems  to  be  done  except  by  occasional 
attacks  of  the  "army  worm."^ 

Probably  the  most  destructive  group  of  leaf-eating 
insects  with  which  the  plant  has  to  contend  is  composed 
of  the  Orthoptera  commonly  known  as  grasshoppers  or 
locusts.-'  During  the  long,  hot  summers  of  regions  far 
inland  these  insects  sometimes  breed  in  such  numbers  as 
to  be  a  serious  meance  to  all  kinds  of  vegetation;  and 
maize  often  affords  during  the  driest  parts  of  the  summer 
the  choicest  green  food  available.  After  severe  attacks, 
there  often  remains  of  the  plant  only  the  stem,  the  leaf 
sheaths  and  midribs,  the  body  of  the  ear,  and  the  roots — 
the  leaf  blades,  silks,  husks,  and  even  the  ends  of  the 
ears  having  been  devoured  (Fig.  55). 

The  earworm,  whose  work  is  so  often  seen  in  roasting 
ears,  attacks  not  only  maize  but  also  tomatoes  and  the 
bolls  of  the  cotton  plant.^  Sweet  corn  is  its  favorite 
variety,  and  the  prevalence  of  the  pest  in  warm  countries, 
where  its  other  hosts  are  grown  extensively,  is  largely 
responsible  for  the  limited  use  that  sweet  corn  has  found 
in  many  sections. 

'  Aphis  maidis-radicis  Forbes  and  A.  maidis  Fitch. 

'  The  larva  of  a  moth,  Cirphus  uni punctata  Haworth. 

3  Family  Acridideae.  The  cicada,  commonly  known  as  the 
seventeen-year  locust,  is  an  entirely  different  insect,  in  no  way  connected 
with  the  life  of  the  corn  plant. 

''  The  earworm  is  the  larva  of  a  moth,  Ildiothis  armigcr  Hubn. 


74  THE  STORY  OF  THE  MAIZE  PLANT 

Grain  in  storage  is  subject  to  the  attack  of  many  de- 
structive insects.  Among  these  are  the  meal  worm,'  the 
Angoumois  grain  moth,^  and  the  grain  weevil.^  In  most 
instances,  the  larvae  are  more  injurious  than  the  adults. 
The  flintiest  grains  are  none  too  hard  for  these  insects, 
and   the  softer  varieties  are  readily  penetrated.     The 


Fig.  55. — Field  of  corn  damaged  by  grasshoppers  (Indiana,  1918) 

damage  done  by  these  pests  is  enormous,  especially  in 
locaUties  where  the  winters  are  not  cold  enough  to  hold 
them  in  check.  Specimens  of  corn  in  museums  and 
laboratories  afford  an  excellent  breeding-place,  and  many 
fine  collections  have  been  ruined  before  the  presence  of 
the  pests  was  detected. 

Remedies  for  the  attack  of  insects. — The  remedy,  if 
there  be  one,  for  the  attacks  of  these  insects  and  other 
animal  enemies  is  a  problem  for  man  rather  than  for  the 

'  Species  of  Tenebrio. 

^  Sitotroga  cercalclla  Oliv.         •>  Calandra  granaria  L.  and  C.  oryzae  L. 


ECOLOGICAL  RELATIONS  75 

plant  to  solve.  When  man  assumed  a  protectorate  over 
the  plant  and  taught  it  the  ways  of  civilized  life,  it  pro- 
ceeded to  lose  many  of  the  protective  devices  that  it 
doubtless  had;  and  today,  in  the  face  of  the  attack  of 
its  myriads  of  enemies,  if  man's  aid  were  withdrawn,  it 
would  meet  with  swift  extinction. 

The  practical  ways  of  dealing  with  birds  and  mammals 
are  obvious.  Trapping  or  poisoning,  and  the  destruc- 
tion of  nests,  dens,  and  other  haunts,  usually  give  results. 
In  the  case  of  the  insects,  however,  the  attack  must  often 
be  much  less  direct;  it  usually  involves  a  thorough  under- 
standing of  the  life-history  of  each  species  of  pest,  and 
an  attack  upon  it  at  the  most  vulnerable  point  in  its  life- 
cycle. 

Many  insects  do  their  worst  damage  near  the  limits 
of  their  range  as  determined  by  temperature  extremes. 
Fall  and  winter  plowing,  and  the  destruction  of  winter 
hiding-places,  will  often  expose  the  eggs,  larvae,  or  adults 
sufficiently  to  enable  cold  weather  and  starvation  to 
finish  their  eradication.  Some  pests  attack  the  plant 
during  only  a  limited  period  in  its  development,  and  these 
can  often  be  discouraged  by  early  or  late  planting,  so 
that  the  plant  reaches  the  critical  stage  at  a  time  unfavor- 
able for  the  insect's  activity. 

Such  insects  as  the  earworm  and  the  chinch  bug,  which 
have  other  hosts  than  maize,  may  be  avoided  by  keeping 
all  such  alternative  hosts  at  some  distance  from  the  corn- 
field. Rotation  of  crops  is  effective  in  dealing  with 
many  insects  whose  principal  or  only  host  is  maize. 

Weevil,  or  other  pests  of  grain  in  storage,  may  be 
eradicated  by  repeated  fumigations  with  carbon  bisul- 
phide.    Well-built  storage  places  which  are  kept  clean 


76  THE  STORY  OF  THE  MAIZE  PLANT 

are  also  an  aid  in  combating  these  insects.  A  single 
half-rotten  ear  of  corn,  in  some  out-of-the-way  place 
where  the  sulphide  fumes  will  not  reach  it,  may  offset 
the  benefits  of  a  very  effective  fumigation  by  maintain- 
ing a  source  of  reinfection.  The  southern  practice  of 
snapping  the  ears  from  the  stalk  and  storing  them  in 
the  husk  is  said  to  be  effective  in  preventing  injury  from 
this  type  of  insect. 

The  encouragement  of  insectivorous  birds  is  one  of 
the  easiest  and  most  effective  ways  of  meeting  the  diffi- 
culty in  many  cases.  Inoculation  with  a  disease- 
producing  fungus'  has  proved  practical  in  controlhng  the 
chinch  bug,  and  it  may  be  possible  to  introduce  epidemics 
among  other  insect  populations  in  a  similar  way. 

Fungous  diseases. — The  fungous  diseases  that  affect 
maize  are  less  numerous  than  the  insect  pests  and  much 
less  destructive.  Many  of  the  parasitic  fungi  are  specific, 
or  practically  so,  in  their  requirements  as  to  host,  and 
they  have  followed  maize  only  tardily  in  its  migrations. 

The  seedlings  of  maize  are  sometimes  attacked  near 
the  ground  by  a  species  of  Pythium,  which  causes  them 
to  die  and  fall  over.  This  disease,  commonly  known  as 
"damping-off,"  is  favored  by  wet  soil  and  poor  ventila- 
tion.    It  is  of  little  economic  importance. 

The  uredo  and  telial  phases  of  two  rusts^  occur  on 
maize  and  its  near  relatives,  causing  red  or  brownish 
pustules  on  the  leaf  blades  and  sheaths.  There  is  a 
marked  variation  in  the  susceptibility  of  individuals  to 
this  disease.  Both  forms  usually  occur  late  in  the 
season,   and   the  damage    done    is    negligible   in   most 

'  Sporolrichium  glohuUjcrum  Spcg. 

=  Piiccinid  Maydis  Bercng.  and  P.  purpurea  Cooke. 


i 


ECOLOGICAL  RELATIONS  77 

irxstances.  The  aecidial  phase  of  one  of  these  parasites 
is  thought  to  occur  on  a  species  of  Oxalis. 

Several  distinct  parasitic  forms  are  responsible  for  a 
frequent  condition  in  which  the  maize  plant  wilts,  and 
its  leaves  turn  white  and  begin  to  die,  at  the  ends, 
without  any  evidence  of  insufficient  moisture  in  the  soil. 
One  of  these  is  due  to  bacteria  which  multiply  in  the 
vascular  tissue  of  the  stem  and  cut  off  the  water  supply 
by  clogging  the  vessels.  A  root  rot  due  to  a  fungus 
often  deranges  the  vascular  functions  in  a  similar  way, 
the  effect  being  in  the  form  of  a  blight.  An  apparently 
different  disease,  or  group  of  diseases,  of  widespread 
occurrence  over  the  United  States,  causes  the  affected 
plant  to  assume  much  the  same  appearance  as  these,  but 
it  has  not  thus  far  been  definitely  connected  with  any 
parasitic  organism.  Its  prevalence  on  soils  having  a 
high  content  of  certain  metallic  mineral  substances 
leads  to  the  belief  that  it  may  prove  ultimately  to  be  due 
to  the  toxic  effect  of  chemicals. 

Following  the  attacks  of  the  earworm,  birds,  or 
squirrels,  as  a  result  of  which  fungous  spores  and  mois- 
ture gain  access  inside  the  husk,  the  whole  ear  or  a  part 
of  it  may  decay.  This  damage,  however,  may  more 
properly  be  charged  to  the  agency  that  opened  the  husk 
than  to  the  fungus  immediately  responsible. 

Similar  to  this  in  appearance  is  the  effect  of  the  specific 
ear-rot  fungus,'  which  enters  the  roots  of  the  youn§  plant 
from  the  soil,  or  from  an  infected  endosperm,  and  makes 
its  way  up  the  stem,  attacking  and  completely  destroying 
the  ear  as  it  nears  maturity.  Certain  species  of  Fusarium 
are  also  known  to  be  responsible  for  similar  ear  rots. 

'  Diplodia  Zcae  (Schw.)  Lev. 


78 


THE  STORY  OF  THE  MAIZE  PLANT 


These  diseases  are  widespread,  and  their  economic 
importance  is  rapidly  coming  to  be  recognized.  Not 
only  do  they  destroy  good  ears  of  corn,  but  certain 
pathological  conditions  in  animals  and  in  man  have  very 
reasonably   been   attributed   to    food    containing    such 

decayed  corn.  Infec- 
tion is  carried  from 
generation  to  genera- 
tion on  the  seed  or  in 
the  stalks  and  de- 
cayed ears  left  in  the 
field  at  husking  time. 
The  best-known, 
and  probably  the  most 
destructive,  disease  of 
maize  is  smut  or 
"brand."'  This  dis- 
ease is  common  in 
every  corn-growing 
country  of  the  world, 
although  it  would  be 
one  of  the  easiest  of 
diseases  to  leave  be- 
hind whenever  corn 
was  taken  into  a  new 
country,  since  the  rather  uncommon  teosinte  is  the  only 
other  host,  and  the  causal  organism  is  not  carried  on  or 
in  the  seed. 

Infection  occurs  at  any  time  during  the  growing 
period  of  the  host,  but  the  fungus  can  gain  entrance 
only  through  wounds,  or  to  succulent,  growing  tissue. 

■  Ustilago  Maydis  (DC.)  Corda. 


Fig.  56. — Smut  on  staminate  inflorescence 


ECOLOGICAL  RELATIONS 


79 


The  floral  parts,  the  nodes,  and  injured  parts  are  especi- 
ally open  to  attack  (Figs.  56-59).  The  effect  is  a  white 
or  greenish  hypertrophied  malformation  consisting  of  the 
tissue  of  the  host  permeated  with  the  mycelium  of  the 
parasite.  As  the  fungus  matures,  these  growths  turn 
black,  due  to  the  segmentation  of  the  mycelium  into  a 
mass  of  black,  dustlike  spores.     These  remain  in  the 


Figs.  57-59. — Smut  on  various  parts  of  the  plant 

field  during  the  winter  and  germinate  in  the  spring, 
immediately  forming  spores  of  another  kind,  which 
proceed  to  infect  a  new  generation  of  the  host. 

This  fungus  destroys  the  ear  in  many  instances, 
and  is  very  objectionable  when  introduced  into  foods 
made  from  the  plant  for  man  or  for  live  stock.  In 
ensilage,  its  effects  are  obvious.  Cattle  that  have  eaten 
large  quantities  of  ears  partly  destroyed  by  smut  some- 
times suffer  from  poisoning  similar  to  that  due  to  the 


So  THE  STORY  OF  THE  MAIZE  PLANT 

ergot  of  rye.'  The  mature  spores  are  uninjured  in  Ihc 
digestive  process,  and  their  presence  in  the  manure  is 
most  favorable  for  the  reinfection  of  the  host. 

With  the  exception  of  smut  and  the  ear  rots,  the 
fungous  diseases  of  maize  cause  relatively  little  damage, 
and  preventive  measures  have  attracted  little  attention. 

The  fact  that  most  of  these  disease-producing  organ- 
isms spend  the  winter  in  the  field,  where  the  corn  was 
grown,  renders  very  effective  such  measures  as  the  rota- 
tion of  crops  and  the  destruction  of  all  diseased  plants 
as  soon  as  they  are  detected.  The  planting  of  uninfected 
seed  is  important  in  dealing  with  the  ear  rots.  The  great 
variation  shown  in  resistance  to  disease  by  different 
varieties  makes  the  selection  of  hardy  strains  an  under- 
taking of  promise. 

Corn  smut  cannot  be  controlled  by  any  of  the  treat- 
ments of  the  seed,  which  are  used  so  successfully  in  the 
case  of  some  of  the  other  cereals  affected  with  smut, 
because  the  spore  that  is  to  infect  the  coming  generation 
is  not  on  or  in  the  seed,  but  remains  in  the  field  during  the 
winter.  The  general  sterility  of  the  plants  affected  by 
smut,  since  the  inflorescence  is  very  often  destroyed, 
tends  naturally  to  eliminate  by  selection  the  suscepti- 
bility to  the  disease. 

'  The  common  practice  of  leaving  in  the  field  at  husking  time  the 
ears  that  have  been  wholly  or  partly  destroyed  by  smut,  and  then  pas- 
turing the  field  with  cattle,  or  other  stock,  is  especially  likely  to  lead  to 
this  trouble,  since  the  animals  spend  the  first  few  days  in  gleaning  the 
ears  that  have  been  left,  and  eat  large  amounts  of  the  fungus. 


CHAPTER  XI 
SEED  AND  PLANTING 

Many  different  varieties  of  maize  are  grown  in  widely 
diverse  lands,  and  the  planting,  cultivation,  and  harvest- 
ing of  the  crop  constitute  a  comprehensive  set  of  pro- 
cesses. But  the  general  principles  involved  are  the  same, 
whether  followed  by  the  scientific  farmer  of  the  Corn 
Belt,  or  in  some  mountain  valley  of  Peru,  where  the 
half-breed  still  manages  his  farm  as  did  his  forefathers 
in  the  days  of  the  supremacy  of  the  Incas. 

The  individual  maize  plant  requires  much  more  space 
than  does  the  individual  of  any  of  its  cereal  relatives, 
and  it  responds  well  to  any  measures  taken  to  conserve 
moisture  and  eliminate  the  competition  offered  by  weeds. 
Grouping  the  plants  in  hills  facihtates  cultivation  and 
aids  in  pollination.  The  Indian  usually  arranged  the 
hills  in  rows,  because  this  was  the  easiest  way  to  space 
them  equally,  and  gave  the  field  a  better  appearance; 
and  the  white  man  adopted  this  method  of  planting  as 
an  adaptation  to  linear  cultivation.  The  methods  of 
manipulation  of  the  corn  crop  in  the  Corn  Belt — ^the 
main  body  of  the  Ohio-Mississippi-Missouri  Valley — are 
the  standard  of  the  world.  More  intensive  methods 
may  be  employed  in  other  localities,  and  higher  yields 
per  unit  of  area  may  be  produced  elsewhere,  but  the 
practice  of  this  section  is  the  type  of  the  highest -scientific 
achievement  in  the  growing  of  corn  on  a  large  scale. 

The  seed  bed. — After  the  removal  of  any  coarse 
debris  left  from   the  crop  of   the  previous  year,    the 


82 


THE  STORY  OF  THE  MAIZE  PLANT 


ground  is  broken.  When  this  work  is  well  done,  a 
layer  of  soil  4  to  8  inches  in  depth  is  completely  inverted, 
and  httle  or  no  vegetable  matter  is  left  uncovered. 

The  next  step  is  to  pulverize  the  soil  and  to  work  it 
down  to  a  compact  seed  bed.  The  method  varies  with 
the  kind  and  condition  of  the  soil  and  with  the  available 
equipment.  The  implement  in  most  common  use  is 
a  spike-tooth  harrow.     A  disk  harrow  may  be  used  to 


Fig.  60. — A  good  field  of  corn  (Indiana,  1921) 


pulverize  deeply  and  produce  a  better  contact  with  the 
subsoil  when  sod  or  coarse  material  has  been  turned 
under.  Various  types  of  rollers  may  be  used  when 
there  are  many  hard  clods  to  be  broken,  and  a  drag  is 
useful  in  pulverizing  an  inch  or  two  at  the  surface. 

In  the  usual  rush  to  get  the  seed  into  the  ground  in 
proper  season,  the  value  of  a  good  seed  bed  is  often 
underestimated.  Thorough  preparation  at  this  time 
may  be  made  to  take  the  place  of  one  or  more  cultivations 


SEED  AND  PLANTING  83 

after  the  corn  has  come  up;  and  the  work  can  be  done 
much  more  thoroughly  and  economically  at  this  time 
than  later  when  the  plants  must  be  guarded  from  injury. 
Moreover,  a  well-prepared  seed  bed  will  better  retain 
moisture  at  a  time  when  the  supply  is  often  deficient, 
and  this  is  conducive  to  uniform  germination  and  a 
good  stand. 

Selection  and  care  of  the  seed. — The  practice  of  selecting 
the  seed  corn  in  the  field,  an  innovation  of  only  the  last 
few  years  in  many  localities,  is  rapidly  becoming  popular. 
Besides  affording  a  better  opportunity  for  judging 
hereditary  qualities  of  the  whole  plant,  this  method 
makes  it  possible  to  take  much  better  care  of  the  seed. 

The  ears  selected  in  the  field  are  dried  as  quickly 
as  possible  by  exposure  to  the  air  while  loosely  arranged 
on  racks  or  shelves.  Artificial  heat  is  often  employed 
advantageously.  After  thorough  drying,  the  seed  should 
be  protected  from  moisture  and  from  extreme  cold  until 
planting  time.  The  popular  idea  that  the  retention  of 
vitality  is  dependent  upon  a  perceptible  amount  of 
moisture  in  the  place  of  storage  is  fallacious.  If  high 
temperatures  are  avoided,  no  place  is  too  dry  for  the 
storage  of  seed  corn.  Fluctuating  humidity  is  especially 
to  be  avoided. 

Viability  and  testing.— Since  viability  is  greatly 
influenced  by  the  conditions  under  which  the  seed  is 
matured,  dried,  and  stored,  the  testing  of  a  few  grains 
from  each  ear  has  been  found  to  be  very  profitable. 

Many  types  of  seed  tester  are  in  common  use,  the 
essential  requirement  being  that  it  provide  small, 
numbered  compartments  affording  conditions  proper  for 
germination.     The  ears  to  be  tested  are  given  numbers 


84  THE  STORY  OF  THE  MAIZE  PLANT 

corresponding  to  those  of  the  compartments  of  the  tester. 
Five  grains  taken  from  different  parts  of  the  ear  constitute 
a  satisfactory  test  portion.  An  ear  that  fails  to  show 
perfect  germination  of  the  seeds  tested  is  usually  rejected. 

The  enthusiastic  beginner  often  makes  the  mistake 
of  surrounding  the  test  seeds  with  conditions  better 
than  those  under  which  germination  normally  takes 
place;  and  this  may  give  positive  results  with  seeds 
whose  vitality  is  too  low  for  field  conditions. 

The  importance  of  seed  testing  is  rapidly  coming 
to  be  recognized.  For  the  effort  spent,  the  farmer 
receives  probably  a  greater  return  from  this  than  from 
any  other  labor  expended  on  the  crop. 

The  well-established  idea  that  seed  corn  that  is  more 
than  a  year  old  will  not  give  satisfactory  results  is  without 
foundation.  Corn  that  is  well  cared  for  retains  its 
vitality  for  at  least  two  years,  and  in  many  cases  much 
longer.^  It  is  often  better  to  use  two-year-old  seed 
from  a  crop  that  is  well  matured  than  one-year-old  seed 
that  has  been  damaged  by  early  frost  or  by  wet  weather 
at  harvest  time.  Few  tests  have  been  made  to  determine 
with  accuracy  the  extreme  limit  of  viability,  but  ten- 
year-old  seed  that  has  been  well  cared  for  has  been  known 
to  give  a  fair  percentage  of  germination.  The  soft 
starchy  and  sweet  varieties  deteriorate  more  rapidly 
than  the  flinty  varieties. 

Grading. — Since  the  principle  involved  in  all  modern 
corn-planting  machinery  presupposes  a  uniformity  in 
the  size  and  shape  of  the  grains,  some  system  of  grading 
the  seed  is  necessary  for  best  results.  The  careful 
selection  of  the  ears  and  the  removal  of  the  imperfectly 

'  See  pp.  33-34. 


SEED  AND  PLANTING  85 

formed  grains  from  the  base  and  the  tip  of  the  ear  are 
usually  sufficient,  but  this  procedure  is  sometimes 
supplemented  or  partly  replaced  by  the  use  of  a  series 
of  grading  screens,  which  remove  all  grains  not  in 
conformity  with  the  adopted  type. 

Hand  planting. — Until  fifty  years  ago  the  hand 
method  of  planting  was  in  general  use,  but  this  work  is 
now  done  better  and  far  more  economically  by  machinery. 
When  the  hand  method  was  employed,  the  field  was  laid 
off  in  furrows,  and  into  these  the  grains  were  dropped 
by  hand,  singly  or  two  or  more  in  a  hill.  A  plow  or  hoe 
was  used  for  covering. 

If  it  were  desired  that  the  hills  be  checkrowed,  the 
field  was  first  marked  in  one  direction  and  then  furrowed 
off  at  right  angles  to  these  marks.  Three  or  four  grains 
were  dropped  in  the  furrow  at  each  intersection  with  a 
mark.  When  carefully  carried  out,  this  method  is 
still  unequaled  for  accuracy.  But  it  is  slow  and  expen- 
sive; the  child  labor  formerly  employed  to  drop  the  seed 
was  a  source  of  much  irregularity;  and  the  stand  was 
often  uneven  because  of  a  lack  of  uniformity  in  the  depth 
of  covering. 

Corn  planters. — The  earliest  corn-planting  machines 
to  be  used  on  an  extensive  scale  were  one-horse  drills, 
which,  at  a  single  process,  opened  a  furrow,  dropped 
the  seed,  and  covered  it,  planting  one  row  at  a  time. 
Better  work  could  be  done,  however,  if  the  furrow  were 
first  opened  with  a  plow.  Within  their  limitations, 
these  usually  did  good  work,  and  they  may  still  be  seen 
in  use  in  many  places. 

A  modem  corn  planter  is  a  highly  developed,  yet 
simple,  piece  of  apparatus.    At  a  single  process  it  plants 


86  THE  STORY  OF  THE  MAIZE  PLANT 

two  rows,  drilled  or  in  hills,  adding  fertilizer  if  desired, 
and  marks  a  line  to  be  followed  in  planting  the  next 
two  rows. 

The  essentially  important  part  of  the  machine^ — and 
the  part  that  has  undergone  most  evolution — is  the 
device  for  releasing  the  grains  at  regular  intervals. 
This  consists  of  a  rotating  circular  plate,  forming  the 
bottom  of  the  seed  box,  and  having  around  its  circum- 
ference a  number  of  holes,  each  of  which  holds  a  single 
grain.  At  the  proper  time  in  the  course  of  a  revolution 
of  the  plate,  each  hole  releases  its  grain  into  a  tube 
leading  to  the  ground.  Interchangeable  plates  afford 
different  sizes  of  holes  for  different  varieties  of  corn, 
and  the  interval  at  which  the  grains  are  dropped  may  be 
modified  by  a  set  of  gears  providing  for  different  speeds 
of  the  revolving  plate. 

The  furrow  for  the  seed  is  opened  by  a  disk  or  by  a 
share  made  of  two  fiat  pieces  of  steel  united  in  front  but 
separated  a  few  inches  at  the  rear.  The  seeds  are 
dropped  into  the  furrow,  and  the  soil  falls  into  the  furrow 
and  covers  them  as  the  implement  passes  on.  The  wheel 
of  the  planter  follows  and  presses  the  soil  firmly.  If 
the  soil  is  heavy,  or  if,  for  other  reasons,  this  pressure 
is  not  desired,  various  adjustments  are  provided  for 
avoiding  it. 

When  the  corn  is  to  be  planted  in  hills,  there  is 
provided  near  the  ground,  in  the  tube  leading  from  the 
seed  box,  a  pocket  which  holds  the  grains  as  they  are 
dropped  until  the  place  for  a  hill  has  been  reached,  when 
all  the  accumulated  grains  are  released  at  once. 

C/ieckr owing.  —This  release  is  usually  accomplished 
by  a  wire  running  across  the  field  parallel  to  the  rows  and 


SEED  AND  PLANTING  87 

passing  through  a  part  of  the  mechanism  of  the  planter. 
At  proper  intervals,  this  wire  has  knots,  which  operate 
the  dropping  device;  and,  as  the  wire  moves  across  the 
field  in  the  progress  of  planting,  each  knot  marks,  by 
its  course,  a  row  at  right  angles  to  the  rows  marked  by 
the  progress  of  the  planter. 

The  checkrow  system  of  planting  offers  many  advan- 
tages over  other  systems,  and  it  is  generally  employed 
throughout  the  Corn  Belt.  It  groups  the  plants  in  a 
manner  conducive  to  effective  pollination,  makes  possible 
cultivation  in  both  directions,  and  greatly  facilitates 
some  methods  of  harvesting. 

Intervals  of  planting. — In  the  Corn  Belt,  the  standard 
distance  between  the  rows  is  3^  feet.  When  the  crop 
is  drilled,  the  individual  grains  are  dropped  at  intervals 
of  12  to  18  inches.  Two  to  four  plants  to  the  hill  is  the 
rule  when  the  checkrow  system  is  used.  Moisture, 
fertility  of  the  soil,  and  special  requirements  of  different 
varieties  determine  the  distance  between  the  rows  or 
between  plants  in  a  row. 

Listing. — A  method  of  planting  extensively  employed 
in  the  arid  regions  of  the  Southwest,  and  also  in  the 
South,  where  the  technique  is  borrowed  from  the  cotton 
industry,  is  known  as  "listing."  The  only  preparation 
of  the  soil  is  the  opening  of  a  deep  furrow  by  means  of 
a  special  type  of  plow.  The  corn  is  planted  in  the 
bottom  of  this  furrow,  which  is  gradually  filled  by 
cultivation  as  the  plants  grow.  Listing  has  the  advan- 
tage of  getting  the  crop  started  early  in  the  spring,  and 
the  deep  planting  is  also  advantageous  in  dry  climates. 


CHAPTER  XII 
TILLAGE 

Probably  no  phase  of  the  complicated  relationship 
between  man  and  maize  is  characterized  by  more 
superstition  and  pretty  theorizing  than  is  the  cultivation 
of  the  growing  plant.  The  uncertainty  on  this  point, 
and  the  error  of  many  methods  of  cultivation,  may  be 
traced  to  a  general  ignorance  of  the  fundamental  prin- 
ciples of  plant  physiology. 

Reduced  to  fundamentals,  the  aims  of  cultivation 
are:  (i)  to  conserve  moisture  in  the  soil  and  increase 
its  capacity  for  moisture;  (2)  to  kill  weeds;  (3)  to  admit 
air  to  the  soil;  (4)  to  aid  the  underground  parts  of  the 
plant  in  penetrating  the  soil;  and  (5)  to  bank  the  soil 
around  the  plants  for  support.  It  is  not  to  be  inferred 
that  the  tiller  of  the  soil  is  always  conscious  of  these 
aims,  or  that  he  need  be  for  successful  results.  He  has 
found,  rather,  a  routine  of  processes  that  give  good 
results,  and  practicability  is  his  guide.  Statistics  show 
that  the  commonest  aim  of  which  the  farmer  is  conscious 
is  the  destruction  of  weeds  ;^  but  a  careful  analysis 
will  doubtless  show  that,  in  many  instances,  the  benefits 
accruing  incident  to  this  aim  are  of  much  greater  value 
than  the  achievement  of  the  aim  itself. 

Conservation  of  moisture. — Under  present  conditions, 

the  conservation  of  moisture  is  the  critical  problem  of 

tillage,  and  the  problem  about  which  least  is  definitely 

understood  by  the  practical  man.     A  dust  mulch  does 

not  induce  capillarity  or  draw  moisture  from  below  in 

'  See  Gates  (18),  pp.  1-2. 

88 


TILLAGE  89 

any  other  way.  It  is  really  effective  in  preventing 
capillarity  in  the  surface  layer,  of  soil. 

In  moist  but  well-drained  soil,  each  minute  particle 
is  wet  with  a  film  of  water,  which  is  held  by  capillarity. 
Deep  down  in  the  soil  there  is  always  a  level  below 
which  all  the  spaces  between  the  particles  are  filled  with 
water.  On  the  other  hand,  the  topmost  layer  of  soil, 
in  contact  with  the  air,  is  continually  losing  its  moisture 
by  evaporation.  Capillarity  not  only  causes  a  film 
of  moisture  to  cling  to  each  particle  of  soil,  but  it  also 
enables  a  dry  particle  to  rob  a  wet  one  of  a  part  of  its 
moisture.  Thus,  each  particle  replenishes  its  supply  of 
moisture  from  particles  below,  and  the  loss  by  evapora- 
tion is  continually  being  replaced  by  a  supply  drawn 
from  the  deep,  saturated  layer. 

In  dry  weather,  this  region  of  saturation  sinks  lower 
and  lower,  and  the  passage  of  water  upward  becomes 
more  and  more  slow.  Any  surface  layer  through  which 
the  water  cannot  pass  by  capillarity  will  diminish 
evaporation  and  leave  more  water  for  plant  life.  Dead 
leaves,  straw,  or  other  vegetable  mulch  may  be  used 
for  this  purpose,  but,  when  a  whole  field  is  to  be  treated, 
the  only  practical  protective  layer  is  one  of  dust,  produced 
by  pulverizing  the  surface  layer  of  soil.  The  pulverizing 
process  leaves  the  particles  of  soil  so  far  apart  that 
moisture  does  not  readily  pass  from  one  to  another  by 
capillarity.  Rain,  pressure,  or  even  the  mere  settling 
of  the  soil  after  a  time,  will  re-establish  these  capillary 
tracks.  Consequently,  the  mulch  must  be  renewed  after 
each  rain,  or  oftener.  A  light  rain,  by  saturating  the 
mulch  without  wetting  the  soil  any  deeper,  may  thus 
do  more  harm  than  good. 


90  THE  STORY  OF  THE  MAIZE  PLANT 

Other  aims. — Although  the  conservation  of  moisture 
is  probably  the  most  important  problem  of  tillage,  and 
other  aims  are  usually  accomplished  incident  to  this, 
yet  the  progress  made  by  weeds  is  not  a  bad  index  to 
use  as  a  guide  for  cultivation.  The  very  conditions 
that  make  weeds  noticeable  also  demand  cultivation  for 
other  purposes.  A  rain,  or  compression  of  the  soil  by 
mechanical  means,  causing  seeds  to'  germinate,  and 
bringing  on  a  crop  of  weeds,  also  necessitates  the  renewal 
of  the  dust  mulch.  Cultivation  definitely  directed 
toward  the  eradication  of  weeds  after  a  long  period 
of  wet  weather  is  also  much  needed  for  aeration  of 
the  soil. 

Implements. — The  most  primitive  horse-drawn  culti- 
vator was  the  single-shovel  plow.  Thorough  cultivation 
with  it  required  ordinarily  five  trips  to  the  row.  This 
type  of  plow  is  still  largely  used  in  many  parts  of  the 
South,  but,  in  the  more  progressive  sections  of  the 
Corn  Belt,  it  was  early  replaced  by  the  double-shovel, 
which  required  the  same  labor  from  the  man,  and 
scarcely  more  for  the  horse,  and  did  the  work  of  cultivat- 
ing a  row  at  two  trips.  The  modern  two-horse  cultivator 
is  two  of  these  double-shovel  plows  fastened  to  a  wheeled 
frame,  one  handle  of  each  having  been  ehminated. 
Many  types  of  this  implement  are  in  common  use,  but 
they  differ  only  in  details.  Some  have  a  tongue,  and 
some  do  not;  some  provide  a  seat,  and  even  a  sunshade, 
for  the  driver;  some  have  only  four  shovels,  but  others 
have  six  or  eight;  almost  all  have  interchangeable 
shovels  of  different  sizes  and  shapes;  and  some  have 
disks  instead  of  shovels.  The  latest  step  in  the  evolution 
of  this  implement  is  the  two-row  cultivator  now  in  use 


TILLAGE  91 

on  many  of  the  larger  farms.  One  man  with  three 
horses,  or  a  tractor,  can  do  with  this  cultivator  ten  times 
as  much  work  in  a  day  as  he  could  do  with  the  old 
single-shovel  plow. 

Various  kinds  of  harrows  and  drags  are  also  in 
common  use,  and  special  plows  for  killing  special  weeds 
or  loosening  special  kinds  of  soil  are  also  used  in  many 
places. 

Processes. — The  corn  plant's  first  struggle  with  its 
environment  is  in  getting  the  young  shoot  out  of  the 
ground.  The  firm  plumule  sheath  usually  makes  its 
way  through  the  soil  very  readily;  but  if  the  soil  is  heavy, 
or  if  a  hard  rain  has  followed  planting,  the  young  plant 
must  be  given  help,  if  its  success  is  to  be  assured.  Some 
type  of  light  harrow  is  often  used  to  break  the  crust  on 
the  soil  at  this  time. 

As  soon  as  all  the  plants  are  up  and  large  enough  to 
be  seen  distinctly,  the  first  thorough  cultivation  is  given. 
Small  shovels  are  ordinarily  used  on  the  cultivator,  and 
the  soil  is  loosened  deep  and  close  to  the  plants.  Sub- 
sequent cultivations  are  shallower.  The  idea  prevalent 
in  many  sections,  that  cultivation  should  be  deep  enough 
to  stir  the  roots,  is  entirely  erroneous.  Anything  that 
tends  to  break  the  roots  or  disturb  their  adjustment  to 
the  soil  is  to  be  regarded  as  a  decided  menace. 

The  number  of  cultivations  varies  with  conditions, 
from  one  to  six  being  given  in  different  places.  If  the 
hills  are  checkrowed,  one  or  more  of  the  plowings  are 
done  at  right  angles  to  the  direction  of  planting.  This 
cross-cultivation  is  one  of  the  most  effective  that  the 
crop  receives,  and  it  is,  in  itself,  ample  justification  for 
the  checkrow  system  of  planting. 


92  THE  STORY  OF  THE  MAIZE  PLANT 

During  the  progress  of  cultivation  the  soil  may  be 
kept  level,  but  there  is  usually  a  tendency  to  throw  it 
toward  the  plants,  forming  a  ridge.  This  practice  is 
intended  primarily  to  give  support  to  the  base  of  the 
plant,  but  recourse  is  often  had  to  it  as  a  more  efficient 
method  of  killing  weeds.  Excessive  ridging  exposes 
increased  surface  to  evaporation  and  is  to  be  condemned 
when  the  conservation  of  moisture  is  a  serious  problem. 

The  use  of  the  two-horse  cultivator  is  terminated  by 
the  growth  of  the  plants  to  a  height  at  which  they  will 
not  pass  under  the  arch  of  the  implement.  In  the  days 
of  the  one-horse  plow,  cultivation  was  often  continued 
far  beyond  this,  even  beyond  the  time  of  flowering; 
but  the  wisdom  of  this  course  is  doubtful,  for,  as  the 
plants  begin  to  shade  the  ground,  and  evaporation  is 
thus  decreased,  a  thick  network  of  fine  roots  is  developed 
near  the  surface,  and  the  damage  done  to  these  usually 
more  than  offsets  the  benefits  of  this  late  cultivation. 
Good  work  can  be  done  at  this  time,  however,  by  means 
of  a  light  drag  just  wide  enough  to  pass  between  the  rows, 
thus  pulverizing  the  soil  at  the  surface  without  disturbing 
the  roots. 


CHAPTER  XIII 
HARVESTING 

Which  of  the  many  and  varied  uses  of  the  corn  plant 
is  to  be  given  chief  prominence  determines  the  method 
of  harvesting.  In  the  matured  grain  is  stored  most  of 
the  material  that  is  useful  to  man,  and  the  process  of 
harvesting  is  usually  centered  about  the  welfare  of  the  ear. 

Pasturing. — When  corn  is  plentiful  and  cheap,  and 
labor  is  expensive  and  hard  to  secure,  recourse  is  often 
had  to  the  simple  expedient  of  turning  live  stock  into 
the  field  to  do  the  harvesting.  The  limitation  of  this 
method  to  practically  the  one  kind  of  stock,  which  cannot 
be  injured  by  overfeeding,  and  assimilates  in  proportion 
to  what  it  eats,  has  given  this  procedure  the  somewhat 
inelegant  name  of  "hogging."  Aside  from  the  saving 
of  labor,  this  method  has  also  the  advantage  of  returning 
to  the  soil  as  manure  all  that  the  best  agricultural 
economics  can  demand.  But  the  fodder  is  a  total  loss, 
and  much  of  the  grain  is  wasted.  Except  under  unusual 
conditions,  as  when  the  crop  is  poor  or  has  been  injured 
by  frost  or  other  unusual  weather  conditions,  or  when 
the  labor  situation  is  unusually  critical,  it  is  more 
profitable  to  take  care  of  the  crop  in  some  other  way. 

Husking  in  the  field. — Throughout  the  Mississippi 
Valley,  the  bulk  of  the  crop  is  left  in  the  field  until 
thoroughly  matured  and  dry  enough  to  be  stored  immedi- 
ately after  harvest.  In  the  absence  of  any  machine 
that  can  make  even  a  pretense  at  this  work,  the  husking 
of  corn  by  hand  has  become  very  much  of  an  art.     The 

93 


94  THE  STORY  OF  THE  MAIZE  PLANT 

only  appliances  used  are  a  husking  peg  and  sometimes 
a  pair  of  gloves  or  some  other  protection  for  the  hands. 
As  the  ears  are  husked  they  are  thrown  into  a  wagon 
which  is  kept  alongside  the  work.  From  the  field  the 
grain  is  taken  directly  to  the  crib. 

The  value  of  the  fodder  is  materially  reduced  by 
weathering  during  the  time  required  for  full  maturity 
of  the  grain,  frost  followed  by  rain  having  an  especially 
deteriorating  effect.  But  after  the  removal  of  the  grain, 
there  is  much  to  be  gained  by  pasturing  the  field  with 
cattle,  sheep,  or  horses  to  harvest  the  fodder  and  glean 
grain  that  has  been  left  in  husking.  The  stalks  left  on 
the  ground  are  broken  down  or  cut  up  with  a  stalk 
cutter  before  the  ground  is  plowed  for  the  next  crop. 

Cutting. — A  varied  group  of  processes,  giving  in 
general  the  maximum  opportunity  for  the  use  of  labor- 
saving  machinery,  have  grown  out  of  the  custom  of 
cutting  and  shocking  the  plants  early  in  the  fall.  The 
proper  time  for  cutting  is  indicated  by  the  loosening  of 
the  dry  husks,  the  plants  being  sufiiciently  dry  at  this 
time  to  be  massed  in  shocks  without  danger  of  molding. 

Until  recent  years,  practically  all  corn  cutting  was 
done  by  hand;  and,  although  efficient  machinery  for 
doing  the  work  has  been  available  for  many  years, 
hand  cutting  still  prevails  in  many  localities.  The 
implement  used  is  a  straight,  heavy  knife  i8  to  24 
inches  long.'  A  support  for  the  beginning  of  the  shock 
is  made  by  weaving  together  the  tops  of  three  or  four 
hills  in  two  adjacent  rows.     Five  or  six  rows  on  each 

'  In  certain  localities  in  Indiana,  there  is  in  use  a  form  of  knife 
which  is  fastened  to  the  shoe,  and  for  which  some  remarkable  results 
are  claimed. 


HARVESTING  95 

side  of  this  "gallows"  are  cut  and  set  around  it,  ten  or 
twelve  rows  of  corn  usually  making  a  shock  row.  The 
shocks  are  spaced  in  the  row  at  about  the  same  interval 
as  the  distance  between  the  shock  rows  (Fig.  61).  The 
finished  shocks  are  tied  with  twine,  cornstalks,  or  some 
other  device. 

A   simple   modification   of   hand    cutting   makes   it 
possible  to  use  advantageously  a  horse-drawn  implement. 


Fig.  61. — Corn  in  the  shock  (Indiana,  192 1) 

This  is  a  sled  or  low-wheeled  wagon,  narrow  enough  to 
pass  between  two  rows,  and  bearing  on  each  side  a 
horizontal  wing  armed  with  a  knife  to  cut  the  stalks. 
The  two  operators  sit  back  to  back  in  the  middle  of  the 
machine,  each  giving  his  attention  to  a  single  row.  The 
stalks  are  grasped  near  the  ear  just  as  the  knife  reaches 
them,  and  held  firmly  until  cut  off.  When  a  shock  is 
reached,  the  machine  is  stopped,  and  the  armfuls  of  plants 
that  have  accumulated  since  the  last  shock  was  passed 
are  set  up.     The  shocks  are  tied  as  when  cut  by  hand. 


96  THE  STORY  OF  THE  MAIZE  PLANT 

Binding. — The  self-binding  corn  harvester  has  been 
improved  to  thorough  dependabihty,  and  is  rapidly 
winning  the  place  that  it  deserves  in  the  manipulation 
of  the  crop.  Taking  a  row  at  a  time,  this  machine  cuts 
the  plants  and  binds  them  in  bundles  of  convenient 
size.  These  are  set  up  in  shocks  in  the  same  manner 
as  the  sheaves  of  the  smaller  grains. 

The  corn  shredder. — The  husking  of  the  corn  that  has 
been  cut  is  often  done  by  hand,  the  fodder  being  fed 
without  further  treatment.  But  much  of  the  advantage 
to  be  gained  from  cutting  the  crop  is  lost  if  use  is  not 
made  of  modern  husking  and  shredding  machinery. 

The  type  of  corn  shredder  in  common  use  today  is 
a  very  efficient  piece  of  machinery.  The  plants,  which 
have  become  thoroughly  dry  in  the  shock,  are  fed  into 
the  machine  between  two  rollers,  which  crush  the  stalks 
and  snap  off  the  ears.  The  latter  fall  into  another  set 
of  rollers  armed  with  small,  hooked  teeth  for  removing 
the  husks.  On  leaving  the  husking  rolls,  the  ears  are 
picked  up  by  an  elevator  and  carried  to  a  wagon  or  other 
receptacle.  The  husks  and  other  fodder  pass  into  a 
shredding  device  from  which  the  macerated  material 
makes  its  way,  through  a  pneumatic  elevator,  to  the 
place  of  storage.  The  shredded  fodder  is  usually  fed 
in  this  form,  but  it  may  be  baled  if  it  is  to  be  transported 
long  distances  or  if  storage  space  is  limited. 

Aside  from  the  labor-saving  phase,  the  shredding 
process  has  other  advantages.  By  loosening  the  leaf 
sheaths  and  husks,  it  makes  available  for  food  the 
maximum  amount  of  fodder.  The  residue  left  by  stock 
also  makes  good  bedding  and  is  an  excellent  absorbent 
for  the  liquid  manure. 


HARVESTING 


97 


Fodder-pulling. — In  some  parts  of  the  United  States, 
mostly  in  the  South,  economic  conditions  make  profitable 
a  practice  known  as  "fodder-pulling."  When  the  leaves 
of  the  plant  are  fully  mature  and  beginning  to  dry,  but 
before  there  has  been  any  deterioration  from  weathering, 
they  are  pulled  off  by  hand  and  hung  over  the  ears  or 

pushed   between    the  

stalks  of  a  hill  to  dry. 
When  dry,  the  fodder 
is  stacked,  or  stored 
otherwise,  until  needed 
(Fig.  62).  Thus,  the 
fodder  is  removed  at 
the  time  of  its  maxi- 
mum value  and  dried 
without  weathering, 
and  the  ear  is  allowed 
to  remain  on  the  stalk 
until    fully    matured. 

Topping. — A  mod- 
ification  of  this 
method  takes  advan- 
tage of  the  fact  that, 
by  the  time  the  leaves 
are  mature,  the  por- 
tion of  the  stem  above  the  ear  is  no  longer  essential 
to  the  perfect  maturity  of  the  grain.  Accordingly,  the 
plant  is  "topped"  just  above  the  ear.  These  tops,  with 
the  leaves  from  the  lower  part  of  the  stem,  are  shocked 
and  left  in  the  field  to  dry. 

When  topping  and  fodder-pulling  have  been  practiced, 
or  when  it  is  desirable  to  save  time  in  harvesting,  the 


Fig.  62. — Stacks  of  "pulled"  fodder 
(Georgia,  1920). 


98  THE  STORY  OF  THE  MAIZE  PLANT 

.ears  may  be  snapped  from  the  stalks  and  stored  in  the 
husks.  The  grain  may  be  fed  to  many  kinds  of  stock 
in  this  condition,  but  it  is  usually  profitable  to  husk  the 
ears  later  and  feed  them  and  the  husks  separately. 

These  hand  methods  of  harvesting,  based  upon 
fodder-pulling,  are  employed  chiefly  on  small  farms  where 
the  crop  is  grown  for  home  use  rather  than  for  com- 
mercial purposes.  It  is  characteristic  of  the  corn  industry 
in  sections  where  corn  is  not  king. 

Ensilage: — Corn  is  more  extensively  used  today 
than  any  other  plant  for  making  ensilage.  For  this 
purpose,  it  is  usually  cut  by  hand  several  days  before 
mature  enough  to  be  cut  and  shocked.  It  is  immediately 
run  through  an  ensilage  cutter,  which  cuts  stems,  leaves, 
and  ears  into  bits,  and  elevates  the  whole  mass  into  a 
silo.  Here  it  is  packed  so  tightly  that  most  of  the  air 
is  driven  out  and  only  the  incipient  stages  of  fermentation 
can  occur.  Practically  the  whole  plant  is  succulent 
and  nourishing  at  this  time.  Ensilage  is  used  chiefly 
for  the  winter  feeding  of  dairy  cattle. 


CHAPTER  XrV 

THE  INFLORESCENCE 

In  its  commonest  and  most  highly  specialized  form, 
maize  is  a  monoecious  plant.  The  staminate  flowers  are 
borne  in  the  tassel,  terminating  the  main  axis  of  the  stem, 
and  the  pistillate  flowers 
in  the  shoot,  a  specialized 
branch  of  the  stem,  which 
bears  a  conspicuous  tuft  of 
red  or  greenish-yellow  silks 
at  flowering  time.  But, 
even  from  the  most  remote 
times  that  have  given  us 
any  account  of  the  plant, 
striking  departures  from 
what  is  considered  the 
normal  condition  have  been 
known  to  occur  frequently.^ 
These  variations  compli- 
cate description,  but  are 
of  material  aid  in  the  in- 
terpretation of  structure 
and  development. 

As  in  all  grasses,  the  flowers  occur  in  definite  spike- 
lets.     Although  the  staminate  and  pistillate  spikelets  are 

'  In  the  days  of  the  early  Spanish  explorations  in  Mexico,  the 
Indians  had  elaborate  religious  ceremonies  centered  about  branched 
ears  of  maize  and  ears  borne  in  the  tassel.  See  Fraser  (64),  p.  173.  The 
Indians  of  Northeastern  North  America  also  attached  peculiar  significance 
to  crooked,  or  otherwise  deformed,  ears.     See  Longfellow's  "Hiawatha." 


Fig.  63. — A  type  of  degeneracy 
produced  by  inbreeding. 


99 


lOO 


THE  STORY  OF  THE  IMAIZE  PLANT 


very  different  in  appearance  at  flowering  time,  they  are 
much  alike  in  essential  details,  and  it  is  evident  that  their 
difference  in  appearance  is  due  to  the  abortion  of  some 


Figs.  64,  65. — A  dwarf   (brachjic)   type  isolated   by  inbreeding. 
This  variety  has  a  very  primitive  form  of  pistillate  inflorescence. 

parts  and  the  unequal  development  of  others.  In  the 
formative  stages  of  development,  every  spikelet  in  either 
inflorescence  has  the  primordia  of  two  perfect  flowers. 

TJie  staminate  inflorescence. — The  staminate  panicle 
varies  in  form  with  the  variety  of  maize  and  the  condi- 


THE  INFLORESCENCE 


tions  of  development.     Its  central  axis  is  the  continua- 
tion of  the  main  vegetative  stem  of  the  plant.     The 


69  70  71 

Figs.  66-71. — Figs.  66,  68,  widely  different  types  of  tassel  found  in 
ordinary  varieties  of  field  corn.  Figs.  67,  70,  reduced  types  resulting 
from  inbreeding.  Fig.  69,  tassel  of  a  Peruvian  variety  grown  in  Indiana. 
Fig.  71,  tassel  with  a  short,  thick  central  spike;  this  character  is  often 
associated  with  the  type  of  ear  shown  in  Fig.  132. 

spikelets  are  borne  on  the  terminal  portion  of  this  axis  and 
on  a  number  of  branches  below  this  terminal  portion. 
These  branches  are  spirally  arranged  around  the  axis,  the 
two-ranked  plan  of  vegetative  structure  being  abandoned. 


I02  THE  STORY  OF  THE  MAIZE  PLANT 

The  tassel  of  a  depauperate  plant  may  be  reduced 
to  the  central  spike  (Fig.  70).  On  the  other  hand,  in 
some  large,  vigorous  varieties  grown  in  a  good  en\'iron- 
ment,  the  tassel  may  be  2  feet  or  more  in  length  and  may 
bear  thousands  of  spikelets.  Secondary  branches  may 
or  may  not  be  present,  and  their  presence  or  absence 
seems  to  be  independent  of  the  size  of  the  inflorescence. 

In  some  varieties,  the 
axes  of  the  spikes  of 
the  tassel  are  thick 
and  rigid,  giving  the 
whole  structure  a 
stiff,  erect  appearance ; 
in  others  these  axes 
are  thin  and  flexible, 
and  a  decidedly  droop- 
ing appearance  is  the 
result.  The  peduncle 
may  be  long  enough 
to  hold  the  inflores- 
cence well  above  the 
leaves,  or  it  may  be 
so  short  that  the  tassel 
is  partly  included  in 
the  sheath  of  the  topmost  leaf.  Certain  wide  variations 
from  this  range  of  form  will  be  described  elsewhere. 

In  all  parts  of  the  staminate  inflorescence,  the  spike- 
lets  are  usually  arranged  in  pairs — one  sessile  and  the 
other  pediceled;  but  groups  of  three  or  four  may  occa- 
sionally be  found  (Figs.  73-75).  On  the  lateral  branches, 
the  pediceled  spikelets  are  symmetrically  arranged  in 
two  rows,  and  abaxial  to  each  of  these  is  the  correspond- 


FiG.  72. — Fruiting  tassel  of  pod  com 


THE  INFLORESCENCE 


ing  sessile  one.  This  gives  the  whole  spike  a  definite 
dorsiventral  aspect,  which  is  lacking  in  the  central 
spike,  where  the  pairs  of  spikelets  are  arranged  in  several 
longitudinal  rows  distributed  around  the  axis.  In 
other  words,  the  lateral  branches  are  distichous  with 
reference  to  the  arrangement  of  their  pairs  of  spikelets, 
and  the  central  axis  is  polystichous  with  respect  to  the 
arrangement  of  the  branches  at  its  base  and  the  spike- 
lets on  its  upper  portion. 
In  its  most  reduced  form, 
however,  when  the  staminate 
inflorescence  consists  of  but 
a  single  spike,  distichism  and 
dorsiventrality  may  be  evi- 
dent in  the  central  spike  as  in 
the  lateral  branches  of  the 
larger  inflorescences. 

The  pistillate  inflorescence.— 
The  forerunner  of  the  "ear" 
of  corn  is  a  unique  structure 
among  the  grasses.  It  is  a 
spike,  on  whose  thickened  axis 
the  paired  spikelets  are  borne  in  several  longitudinal  rows, 
as  are  the  staminate  spikelets  on  the  central  axis  of  the 
tassel.  Each  row  of  pairs  of  spikelets  contributes  to  the 
make-up  of  the  ear  two  rows  of  grains,  this  explaining 
the  regular  occurrence  of  an  even  number  of  rows  of  grains 
on  the  ear  (Figs.  76,  77).  Both  spikelets  in  the  pair 
are  usually  sessile,  and  the  two  are  indistinguishable 
except  in  early  stages  of  development. 

Sexual  anomalies. — The  unstable  sexual  condition  of 
the  flowers  of  maize,  and  the  possibility  of  the  develop- 


FlGS.    73-75 
spikelets. 


I04  THE  STORY  OF  THE  MAIZE  PLANT 

ment  of  the  wrong  set  of  floral  essentials  in  an  inflo- 
rescence, lead  to  the  frequent  occurrence  of  anomalies. 
Some  of  these,  which  aft'ect  only  the  spikelets  or  the 
flowers,  will  be  discussed  in  the  next  chapter.  Others, 
however,  affect  the  entire  inflorescence. 

It  is  believed  by  some  that  maize  represents  a  step 
in  the  expression  of  an  orthogenetic  tendency  toward 
dioecism.  The  peculiar  structure  of  the  plant  indicates 
that  the  culmination  of  this  process  is  improbable  as 


Figs.  76,  77. — End  views  of  the  basal  and  tip  portions  of  a  broken 
ear,  showing  pairing  of  rows  of  grains. 

long  as  maize  remains  a  cultivated  plant,  for  this  would 
materially  decrease  its  usefulness;  but  the  problem  is 
an  interesting  one  botanically. 

Sterile  plants,  having  normal  tassels  but  no  pistfllate 
branches,  frequently  occur  in  cornfields  and  often  con- 
stitute a  factor  of  perceptible  importance  in  decreasing 
the  yield.  This  tendency  toward  dioecism  is  thought 
to  be  inherited,  and  the  eUmination  of  such  plants  before 
the  maturity  of  their  pollen  is  of  importance. 

The  evolution  of  purely  pistillate  plants  seems  much 
less  probable,  for  it  would  require  the  elimination  or 


THE  INFLORESCENCE  105 

complete  metamorphosis  of  the  tassel.  Certain  tend- 
encies in  the  latter  direction  by  plants  grown  in  the 
greenhouse  in  the  winter,  and  by  the  pistillate  tassels 
of  pod  corn  (Fig.  72),  are  probably  not  to  be  regarded  as 
very  significant.  The  nearest  approach  to  dioecism  in 
the  future  evolution  of  the  plant  is  in  the 
development  of  dimorphism,  one  form  being 
monoecious  and  the  other  staminate. 

The  central  spike  of  the  tassel,  and  less 
often  the  branches  of  this  structure,  may, 
for  a  part  of  their  length,  assume  the  form 
of  the  pistillate  spike  and  produce  fruits, 
the  remainder  of  the  inflorescence  being  of 
the  normal  staminate  form. 

A  common  anomaly  of  the  ear  occurs 
through  the  replacement  of  a  part  of  the 
pistillate  spikelets  with  staminate  units. 
The  commonest  form  of  this  is  the  ear  with 
a  staminate  tip  (Fig.  78),  whose  axis  is 
slender  like  that  of  the  central  spike  of  the 
tassel.  Less  commonly  the  staminate  por- 
tion is  at  some  distance  from  the  tip, 
between  two  pistillate  portions  (Fig.  80).  Fig.  78.— Ear 
Small  groups  of  staminate  spikelets  may  with  staminate 
also  occur  anywhere  on  the  ear.  *^P' 

At  the  point  where  the  androgynous  spike  changes 
from  one  type  of  spikelet  to  the  other  are  often  found 
transitional  forms,  where  the  two  spikelets  of  a  pair,  or 
the  two  flowers  of  a  spikelet  are  not  ahke.  In  such 
instances,  there  is  a  marked  tendency  for  the  lower 
elements  of  the  pair  to  be  pistillate  and  the  upper 
staminate. 


io6 


THE  STORY  OF  THE  MAIZE  PLANT 


Functionally  perfect  flowers  also  occur,  but  the 
definite  protogyny  of  the  inflorescence,  and  the  inclosing 
sheath  of  husks  on  the  ear,  where  hermaphrodite  flowers 
are  most  common,  usually  render  the  pollen  of  no  avail. 


ai 


t 


Figs.  79-81. — Fig.  79,  fasciated  ear.  Fig.  80,  ear  witli  starainate 
portion  at  some  distance  from  tip.     Fig.  81,  branched  ear 

Branched  ears. — Several  distinct  types  of  branching 
occur  anomalously  in  the  ear,  and  no  general  explana- 
tion of  these  is  possible  (Figs.  79  and  81).  Some  are 
doubtless  due  to  environmental  influences,  while  others 
are  deep  seated  in  origin  and  have  not  yet  been  explained. 

A  variety  has  been  isolated  in  which  the  pistillate 
inflorescence  is  a  panicle  much  like  that  of  kafir  corn  or 
other  sorghums.     The  tassel  of  this  variety  is  also  more 


THE  INFLORESCENCE 


107 


diffuse  than  that  of  the  normal  plant  (Figs.  84  and  86- 
91).  This  is  a  hereditary  anomaly  recessive  in  behavior. * 
The  base  of  the  otherwise  normal  ear  is  sometimes 
surrounded  with  a  whorl  of  branches,  each  bearing  four 
or  more  rows  of  grains  (Fig.  82).  These  branches  are 
probably  reversional  suggestions  of  those  lost  in  the 
evolution  of  the  shoot  when  the  inflorescence  was  drawn, 
phylogenetically  speaking,  into  the  leaf 
sheaths  by  the  contraction  of  the  axis 
of  the  pistillate  shoot.  The  branches 
of  the  pistillate  shoot,  which  sometimes 
occur  as  small  ears  in  the  axils  of  the 
husks,  are  in  no  way  the  equivalent  of 
these    branches    at    the    base    of    the 


Tig  82  —Ear 
with  branches  at 
base. 


Fasciation  sometimes  occurs  at  the 
tip  of  the  ear,  the  structure  at  this  point 
being  flattened  and  slightly  divided 
into  many  growing-points.  This  anom- 
aly seems  to  be  inherited  in  some  vari- 
eties (Fig.  79). 

The  bifurcate  or  three-parted  ears 
often  encountered  are,  as  a  rule, 
fluctuating  anomalies  of  development,  having  no  evolu- 
tionary significance  (Fig.  81).  They  may  be  produced 
artificially  by  injuries  to  the  plant  during  development. 
One  or  more  hereditary  cases  of  this  anomaly  have  been 
reported,  but  there  is  nothing  to  indicate  that  they 
represent  anything  more  than  sporadic  mutations. 

The  inflorescence  of  suckers. — -The  variable  terminal 
inflorescences  of  suckers  range  all  the  way  from  the 

'  Gernert  (68).  ^  See  p.  58  and  Figs.  44  and  45- 


io8 


THE  STORY  OF  THE  MAIZE  PLANT 


nonnal  ear  to  the  normal  tassel.  Some  suckers  remain 
sterile  throughout  the  life  of  the  plant,  the  terminal 
inflorescence  being  rudimentary  or  entirely  lacking. 
Others  are  Hke  normal  pistillate  branches  except  that  they 
grow  low  on  the  plant  and  take  root  in  the  soil.  Larger 
and  more  vigorous  shoots  have  this  pistillate  portion 
surrounded  by  a  number  of  staminate  or  androgynous 


Figs.  83-85. — Fig.  8$,  a  tj-pe  of  conical  car,  luuing  eighteen  rows 
of  grains  at  the  base  and  ten  at  the  tip.  Fig.  84,  ear  of  branch  corn. 
Fig.  85,  an  androgj'nous  ear. 

branches,  and  all  gradations  occur  between  this  and  the 
normal  staminate  panicle  of  large,  well-developed  suckers 
having  ears  of  their  own  (Figs.  92-94). 

The  conditions  determining  the  form  of  the  inflo- 
rescence of  the  suckers  have  never  been  investigated  in 
detail.  Heredity  plays  an  important  part,  but  Hght, 
moisture,  and  nourishment  are  probably  to  be  considered. 
The  extent  of  the  root  system  of  the  sucker,  and  the 
consequent  degree  of  independence  of  the  latter,  are 
influential.     These  factors  may  also  be  complicated  by 


THE  INFLORESCENCE 


109 


the  relation  between  the  physiological  acti\ities  of  the 
main  shoot  and  the  time  at  which  the  primordia  of  the 
inflorescences  of  the  suckers  are  differentiated. 


jTse  90 

Figs.  86-91.— Tassel  and  staminate  spikelets  of  branch  com 


92  93  94 

Figs.  92-94. — Inflorescences  of  suckers 


I  lO  THE  STORY  OF  THE  MAIZE  PLAXT 

The  origin  of  the  ear. — The  structure  of  the  ear  is  the 
distinguishing  characteristic  of  the  species;  and  around 
it  and  its  homologue,  the  central  spike  of  the  tassel, 
have  centered  most  of  the  theoretical  considerations  as 
to  the  origin  of  maize.  The  ear  has  probably  been 
evolved  from  a  pistillate  panicle  similar  in  form  to  the 
present  staminate  inflorescence-.  The  loss  of  the  lateral 
branches  from  this  primitive  structure  was  evidently 
correlated  with  the  phylogenetic  shortening  of  the  inter- 
nodes  of  the  ear-bearing  branch,  and  the  consequent 
invagination  of  the  inflorescence  by  the  leaf  sheaths, 
which  are  now  the  husks  of  the  ear. 

Distichism  in  the  arrangement  of  the  vegetative 
parts  of  the  grasses  is  usuaUy  continued  into  the  inflo- 
rescence, and  this  is  to  be  regarded  as  a  primitive  char- 
acteristic. The  paired  spikelets  of  the  branches  of  the 
tassel  of  maize,  and  in  both  the  inflorescences  of  teosinte, 
are  distichously  arranged.  But  the  same  units  in  the 
ear  and  on  the  central  spike  of  the  tassel  in  maize  are 
polystichous  in  arrangement,  as  are  the  branches  of  the 
tassels  in  both  maize  and  teosinte.  In  the  tassel  of  teo- 
sinte, there  seems  to  be  no  true  homologue  of  the  terminal 
spike  of  the  tassel  in  maize.  The  real  problem,  then,  is 
reduced  to  an  explanation  of  polystichism  in  the  arrange- 
ment of  parts  around  the  central  axis  of  the  inflorescence. 

Of  the  many  attempts  that  have  been  made  to  explain, 
wholly  or  in  part,  the  evolution  of  this  peculiarity  in  the 
inflorescence,  four  or  five  have  resulted  in  theories  that 
may  be  cited  as  having  made  definite  progress. 

Among  the  first  to  give  the  matter  serious  attention 
was  Hackel  (71) ,  who  attributes  the  origin  of  the  ear  to  a 
hereditary   anomaly   of   the  nature  of   fasciation.     He 


THE  IXFLORESCEXCE  iii 

makes  no  attempt  to  show  a  definite  homology  between 
the  new  structure  and  the  parent-tj-pe,  and  this  is  chiefly 
where  his  theory  fails  to  give  satisfaction.  It  discourages 
investigation  without  really  explaining  anything. 

The  next  definite  Une  of  reasoning  on  the  problem 
assumed  that  the  ear  had  resulted  from  the  lateral 
fusion  during  development  of  two  or  more  pistillate 
spikes  similar  in  structure  to  the  distichous  branches  of 
the  stamina te  inflorescence.'  This  theory  is  the  preva- 
lent explanation  of  the  problem.  Out  of  opposition 
to  this  theory  developed  the  idea  of  the  homology 
between  the  pistillate  inflorescence  and  the  terminal 
spike  of  the  tassel,^  and  the  fusion  idea  is  generally  held 
as  a  reasonable  explanation  of  both  structures. 

If  the  theory  were  well  founded,  however,  we  should 
expect  to  find  in  the  development  of  the  structures  in 
question  some  indication  of  their  pecuHar  phylogeny, 
but  such  evidence  is  lacking.  The  young  ear  and  the 
young  tassel  develop  from  ordinary  growing-points  with 
nothing  to  suggest  a  compound  nature,  and  nothing  to 
explain  why  their  lateral  ramifications  are  developed 
in  several,  instead  of  in  two,  rows. 

But  the  weakest  point  in  the  theory  is  its  failure  to 
account  for  ears  having  rows  not  in  multiples  of  four. 
Each  spike  contributing  to  the  formation  of  the  ear  its 
two  rows  of  paired  spikelets  would  account  for  four 
rows  of  grains.  Ears  with  eight,  twelve,  sixteen,  or 
twenty  rows  of  grains  would  be  expected;  but  ten, 
fourteen,  or  eighteen  rows  would  be  impossible;  and 
the  frequency  with  which  the  latter  numbers  occur 
constitutes  a  serious  inconsistency. 

'  Harshberger  (74).         -  Collins  (24)  and  Montgomen-  (no). 


112  THE  STORY  OF  THE  MAIZE  PLANT 

Another  theory  has  the  polystichous  organ  evolved 
from  the  upper  part  of  a  hirge,  dififuse  panicle,  by  the 
reduction  of  branches  to  pairs  of  spikelets.*  The  ear 
and  the  tassel  of  one  peculiar  variety  of  corn  suggests 
this  origin,  and  the  theory  seems  consistent  with  all 
available  facts.^"  But  it  falls  short  of  a  complete  explana- 
tion, for  it  evades  explanation  of  the  origin  of  poly- 
stichism  in  this  more  primitive  inflorescence. 

A  recent  theory^  suggests  that  the  ear  has  resulted 
from  the  shortening  and  twisting  of  a  two-rowed  pistillate 
spike,  accompanied  by  an  increase  in  the  number  of 
pairs  of  spikelets,  and  by  the  yoking  of  adjacent  pairs. 
This  idea  has  some  points  in  its  favor,  but  it  must  be 
modified  in  some  respects  and  supported  by  certain 
further  observations  before  it  can  be  accepted  more  than 
tentatively.  It  is  unfortunately  based  upon  the  sug- 
gestive structure  of  the  pistillate  spikes  of  hybrids 
between  maize  and  teosinte,  and  these  are  of  doubtful 
value  as  indicating  the  character  of  either  parent-genus. 
The  corollary  explanation  of  the  structure  of  ears  of 
corn  with  more  rows  at  the  base  than  at  the  tip  is 
certainly  untenable,  being  based  apparently  upon  the 
external  appearance  of  the  mature  ear,  which  is  but  a 
poor  expression  of  the  internal  structure."* 

The  last  word  has  not  yet  been  said  on  the  evolution 
of  the  ear  of  corn,  and  it  cannot  be  said  until  further 

'  Collins  (24).  =  See  Figs.  86-91. 

3  Collins  (30). 

1  The  difference,  when  there  is  any,  between  the  number  of  rows  of 
grains  at  the  base  of  an  ear  and  the  number  at  the  tip  is  always  a  multiple 
of  two,  and  there  is  no  place  on  the  ear  at  which  an  odd  number  of  rows 
can  be  found  in  following  around  a  circumference.  Collins  (30)  attributes 
this  to  a  sort  of  sympathetic  "yoking  "  between  each  pair  of  spikelets  and 
a  pair  almost  diametrically  opposite  it  on  the  ear.  He  states  that  the 
loss  in  number  of  rows  noted  in  examining  an  ear  from  base  to  tip  is  due 


THE  INFLORESCENCE  113 

researches  have  corrected,  amplified,  and  evaluated  the 
data  now  at  hand,  and  woven  the  results  into  a  harmoni- 
ous fabric  of  theory. 

These  investigations  will  be  made  from  many  differ- 
ent points  of  view  and  along  very  different  lines,  and 
no  small  part  of  the  task  will  be  to  sort  out  the  signifi- 
cant from  the  irrelevant.  The  most  fruitful  field  seems 
to  be  in  a  broad,  yet  detailed,  study  of  the  comparative 
morphology  of  the  inflorescences  of  many  grasses,  with  the 
results  all  referred  back  to  the  problems  offered  by  maize. 
Anomalous  inflorescences  will  doubtless  contribute  valu- 
able information,  but  the  investigator  must  avoid  the 
common  error  of  considering  every  anomaly  a  reversion. 

Hybrids  between  maize  and  teosinte  will  always 
exhibit  suggestive  series;  but,  until  we  are  more  sure 
of  the  homologies  between  these  two  genera,  it  is  futile 
to  expect  much  information  from  the  hybrids,  for  they 
will  be  speaking  in  a  language  that  we  cannot  understand. 
When  the  true  homologies  of  their  inflorescences  are  clear, 
then  these  hybrids  may  afford  checks  upon  our  concep- 
tions of  morphology;  but  they  will  never  alone  constitute 
valid  constructive  evidence  as  to  phylogenetic  relation- 
ships or  the  course  of  evolution.  Interaction  between 
closely  related  entities  is  capable  of  giving  rise  to  mon- 
strosities that  defy  explanation  in  terms  of  the  relation- 
ships of  the  parent-stocks;  and  only  a  sound  working 
basis  of  morphology  will  save  the  investigator  from  the 
lure  of  suggestive  analogy. 


to  the  dropping  of  one  spikelet  from  each  pair  in  a  row  of  paired  spikelets, 
and  the  simultaneous  dropping  of  one  from  each  pair  in  the  "yoked" 
row  of  paired  spikelets  on  the  other  side  of  the  ear.  But  the  writer  has 
shown  (156)  that  by  shaving  the  chaff  from  the  cob,  as  when  a  corncob 
pipe  is  to  be  made,  it  can  be  demonstrated  that  the  loss  in  number  of 
rows  is  really  due  to  the  dropping  of  an  entire  row  of  pairs  of  spikelets. 


CHAPTER  XV 
SPIKELETS  AND  FLOWERS 

The  spikelet  of  any  species  of  grass  usually  exhibits 
a  limited  range  of  variation.  The  general  habit  of  the 
plant,  the  anatomy  of  its  vegetative  parts,  and  the  size 
and  form  of  its  inflorescence  may  vary  widely  with 
environment;  but,  though  a  luxuriant  specimen  may 
have  a  thousand  spikelets,  and  a  depauperate  individual 
of  the  same  species  but  a  single  one,  there  is  a  tendency 
on  the  part  of  each  species  to  maintain  a  high  degree  of 
uniformity  in  the  structure  of  its  spikelets.  This  gives 
to  the  spikelet  a  very  considerable  weight  in  the  deter- 
mination of  the  identity  and  relationships  of  the  species. 

The  spikelet  of  a  grass  consists  of  an  aggregation  of 
flowers  and  bracts  more  or  less  compactly  arranged 
alternately  in  two  rows  on  a  common  axis,  the  rachilla. 
At  the  base  of  the  spikelet  is  usually  a  pair  of  empty 
bracts,  the  glumes,  and  above  these,  one  or  more  similar 
structures,  the  lemmas,  the  number  of  the  latter  varying 
with  the  species,  and,  to  a  certain  extent,  with  conditions. 
From  the  axil  of  each  lemma  arises  a  short  branch, 
bearing  on  its  adaxial  side  a  single  bract,  the  palea, 
and  terminated  by  a  flower. 

The  flower  consists  of  a  pistil,  one  to  six  stamens, 
and  two  or  three  lodicules.  The  lodicules  are  probably 
the  metamorphosed  remnants  of  a  perianth.  Their 
function  is  to  open  the  spikelet  by  forcing  back  the  lemma 
at  the  time  of  flowering.  Variations  from  this  typical 
structure  of  the  spikelet  and  flower  can  usually  be 
attributed  to  the  abortion  of  one  or  more  parts. 


SPIKELETS  AND  FLOWERS 


115 


A  sharp  line  of  distinction  may  be  drawn  between 
one  group  of  genera,  in  which  the  spikelet  is  indetermi- 
nate, and  another  in  which  it  is  determi- 
nate. In  the  one,  the  lower  flower  is 
the  most  advanced  in  development,  and 
abortion  of  parts  is  most  likely 
to  occur  at  the  top;  in  the 
other,    this    order  is  reversed. 

It  is  among  the 
grasses  having  deter- 
minate spikelets  that 
maize  finds  its 
place.  Both  the 
staminate  and  pis- 
tillate spikelets  are 
modifications  of  a 
two-flowered  prim- 
itive type  in  which 
the  upper  flower  is 
the  more  advanced 
in  development, 
and  in  which  cer- 
tain  parts  are 
suppressed  in  de- 
velopment. 

The  staminate  spikelet. — The  staminate  spikelet  is  a 
rounded,  somewhat  laterally  compressed  structure,  borne 
with  its  edge  toward  the  rachis.  The  other  parts  of  the 
spikelet  are  completely  inclosed,  previous  to  flowering, 
by  the  two  firm,  ovate,  overlapping  glumes  (Fig.  95). 

^  This  is  not  an  infallible  mark  of  distinction  between  the  two  great 
subfamilies  of  grasses  recognized  in  current  systematic  practice,  but  it 
is  probably  the  most  significant  single  point  of  variation  in  the  family. 


Fig.  95. — A  pair  of  staminate  spikelets 


ii6 


THE  STORY  OF  THE  MAIZE  PLANT 


The  lemma  and  palea  are  thinner  and  more  abruptly 
pointed,  or  even  rounded  at  the  tip.  The  glumes  are 
more  or  less  pubescent,  but  the  other  bracts  are  gla- 
brous. The  rachilla  is  very  short,  and  the  upper 
flower  is  apparently  ter- 
minal. 

In  the  flower  proper,  the 
three  stamens  are  about 
equally  spaced  around  the 
somewhat  triangular  recep- 
tacle, one  being  dorsal  and 
the  other  two  next  to  the 
palea.  The  two  lodicules 
are  located  dorsally,  alter- 
nating with  the  stamens. 
In  the  vascular  system  of  the 
receptacle,  there  is  a  sug- 
gestion that  the  flower  may 
at  one  time  have  had  a  third 
lodicule.  In  the  middle 
of  the  receptacle  is  a  rudimentary  pistil  (see  Figs.  96 
and  07). 

The  pistillate  spikelet. — The  parts  of  the  primi- 
tive two-flowered  spikelet  have  undergone  much 
more  modification  in  the  pistillate  than  in  the  stam- 
inate  spikelet.  The  glumes  are  thick  and  fleshy  and 
do  not  completely  inclose  the  other  parts  of  the 
spikelet.  Their  pubescence  is  rudimentary.  The 
lemmas  and  paleas  are  thinner  and  shorter  than  the 
glumes. 

Normally,  the  only  part  remaining  functional  of 
either  flower  of  this  spikelet  is  the  pistil  of  the  upper 


Fig.  96. — Diagram  of  cross- 
section  of  staminate  spikelet. 
G,  glume;  Le,  lemma;  5,  stamen; 
Pa,  palea;  Pi,  pistil(rudimentary) ; 
Lo,  lodicule. 


SPIKELETS  AND  FLOWERS 


117 


flower.  Irregularly  distributed  around  its  base  are  three 
rudimentary  stamens.  The  lodicules  are  seldom  visible 
at  anthesis.  The  entire  lower  flower 
is  aborted,  but  the  rudiments  of  its 
essentials  are  always  present.  The 
lodicules  are  usually  much  better  de- 
veloped than  those  of  the  upper  flower, 
but  they  are  apparently  functionless 
(see  Fig.  98). 

Sexual  anomalies. — Most  of  the 
anomalies  of  the  spikelet  or  of  the 
flower  are  due  to  the  functioning  of 
some  parts  usually  abortive.  Those 
of  commonest  occurrence  are  perfect 
flowers,  androgynous  spikelets  or  pairs 
of  spikelets,  and  spikelets  of  reversed 
sexuality. 

Functionally  perfect  flowers  are 
of  rare  occurrence.  They  are  due  to 
the  development  of  either  stamens  in 
the  ear  flowers  or  pistils  in  the  flowers 
of  the  tassel.  The  latter  usually 
produce  fruits  (Fig.  72),  and  their 
silks  are  often  divided  into  two  dis- 
tinct styles  and  stigmas,  as  was 
doubtless  the  condition  in  the  prototype  of  maize.  The 
stamens  of  perfect  flowers  in  either  the  ear  or  the  tassel 
may  be  normal,  or  they  may  show  various  types  of 
abortion.  Sometimes  only  one  of  the  three  stamens  of 
a  flower  is  functional,  or  even  fully  developed  in  form; 
and,  in  such  cases,  it  is  usually  the  dorsal  one  that  makes 
greatest  development. 


Fig.  97.— Diagram 
of  longitudinal  section 
of  staminate  spikelet. 
G,  glume;  L,  lemma; 
P,  palea;  S,  stamen; 
Pi,  rudimentary  pistil. 


ii8 


THE  STORY  OF  THE  MAIZE  PLANT 


In  both  inflorescences  the  metamorphosis  of  a 
spikelet  is  often  a  complete  change  of  sex.  When  a 
tassel  spikelet  becomes  pistillate,  it  often  loses  its  stamens 
and  influences  the  glumes  and  a  section  of  the  rachis  to 
assume  the  characteristics  of  the  pistiUate  axis.  On 
becoming  staminate,  a  spikelet  of  the  ear  assumes  the 
staminate  form  of  glumes,  and  elevates  itself  on  a  pedicel 


Figs.  98-99. — Fig.  98,  diagram  of  longitudinal  section  of  pistillate 
spikelet.  St,  base  of  style;  Sc,  stylar  canal;  /,  integuments;  G,  glume; 
L,  lemma;  P,  palea;  F,  rudimentary  flower;  E,  embryo  sac;  S,  rudi- 
mentary stamen.  Fig.  99,  longitudinal  section  of  the  two-flowered  spike- 
let of  Coimtry  Gentleman  sweet  corn. 

if  it  be  potentially  the  pedicellate  one  of  the  pair.  If 
enough  spikelets  in  a  group  are  thus  metamorphosed, 
the  rachis  also  assumes  the  character  of  the  same  struc- 
ture in  the  tassel.  If  only  one  spikelet  of  a  pair  changes 
its  sex,  it  is  usually  the  sessile  one  of  the  staminate  unit, 
and,  almost  invariably,  the  pediceled  one  of  the  pistillate 
unit,  that  is  affected. 

Compound  spikelets. — Terminating  any  branch  of  the 
tassel  may  often  be  found  an  abnormal  spikelet  having 


SPIKELETS  AND  FLOWERS 


more  than  two  flowers,  and  sometimes  more  than  two 
glumes.  A  common  form  of  the  anomaly  is  a  structure 
subtended  by  a  whorl  of  three  or  more  glumes.  Dis- 
section proves  these  anomahes  to  be  due  to 
the  coalescence  of  two  or  more  spikelets. 
They  probably  have  no  morphological  sig- 
nificance. 

Two-flowered  pistillate  spikelets. — Regu- 
larly in  one  or  more  varieties  of  sweet  corn/ 
and  occasionally  in  any  variety  of  corn, 
both  flowers  of  the  pistillate  spikelet  are 
well  developed,  and  two  grains  are  produced 
in  each.  When  this  occurs  throughout  the 
ear,  it  doubles  the  number  of  grains  on  the 
cob  and  leads  to  the  characteristic  "shoe- 
peg"  shape  and  irregular  arrangement  of 
the  grains  (Figs.  loo  and  167). 

Development  of  the  spikelets. — The  simi- 
larity in  structure  between  the  pistillate 
and  staminate  spikelets  is  well  brought  out  ^^^  °^  Country 
in  their  development  (Figs.  101-7).  At  the  g^^ee'tcorn'^ith 
time  of  their  first  appearance,  the  two  types  many  starchy 
are  exactly  alike.  The  homologous  parts  grains  due  to 
of  the  two  appear  in  the  same  order,  and 
follow  the  same  course  in  development,  until  they  begin 
to  diverge  in  appearance  because  of  the  suppression  of 
parts. 

The  primordium  of  a  pair  of  spikelets   makes  its 
appearance  as  a  rounded  protuberance  on  the  floral  axis. 


Fig. 100 


'  This  is  a  regular  occurrence  in  the  spikelets  of  Country  Gentleman 
and  Ne  Plus  Ultra  sweet  corn. 


THE  STORY  OF  THE  MAIZE  PLANT 


This  soon  divides  into  two  somewhat  unequal  parts, 
the  primordia  of  the  two  spikelets.     In  each  spikelet 

G- 


Figs.  101-7. — Sections  of  spikelets  showing  development:  Figs. 
101-3,  spikelets  undifferentiated  as  to  sex.  Figs.  104,  106,  pistillate 
spikelets.  Figs.  105,  107,  staminate  spikelets.  G,  glume;  S,  stamen; 
Si,  style;  P,  palea;  L,  lemma;  O,  ovule;  Pi,  pistil. 


SPIKELETS  AND  FLOWERS  I2I 

the  lower  glume  is  the  first  differentiation  to  appear, 
and  it  is  soon  followed  by  the  upper  glume,  and  this  by 
the  two  lemmas.  By  a  division  of  the  growing-point, 
the  meristematic  region  now  develops  a  large  upper 
lobe  and  a  smaller  lower  one,  the  primordia  of  the  two 
flower-bearing  branches.  On  the  upper  one  of  these, 
the  palea  is  soon  differentiated,  but  that  of  the  lower 
flower  is  late  in  making  its  appearance. 

In  the  ontogeny  of  the  flower,  the  stamens  first 
appear,  and  then  the  lodicules;  and  the  part  that  remains 
becomes  the  primordium  of  the  pistil.  The  detailed 
aspect  of  each  of  these  organs  is  dependent  upon  the  kind 
of  flower,  staminate,  or  pistillate,  in  which  it  is  developed. 
The  two  flowers  of  the  staminate  spikelet  are  alike 
in  all  homologous  steps  of  normal  development,  but  the 
upper  is  considerably  in  advance  of  the  lower. 

The  development  of  the  stamen  offers  no  problems 
essentially  pecuUar  to  maize.  Cross-sections  of  the 
anther  at  the  time  of  the  heterotypic  division  show  the 
pollen  mother-cells  surrounded  by  three  layers  of  tapetal 
cells.  The  subepidermal  mechanical  layer,  instrumental 
in  opening  the  anther,  is  present  for  only  a  short  distance 
at  the  distal  end  of  the  anther  (Fig.  109).  As  a  result, 
the  anther  opens  by  only  a  small  pore  (Fig.  95).  As 
the  sporogenous  tissue  develops,  the  tapetum  is  absorbed 
until  only  the  epidermis  and  mechanical  layer  are 
present  at  maturity  (Figs.  108,  109). 

The  two  small  protuberances  arising  soon  after  the 
stamens,  and  alternate  with  them,  develop  into  the 
lodicules.  At  maturity,  these  are  usually  short,  plump, 
truncate  bodies,  but  they  often  bear  terminal  leaflike 
appendages  also.     A  generous  quota  of  vascular  tissue 


122  THE  STORY  OF  THE  MAIZE  PLANT 

enables  them  quickly  to  become  turgid  when  they  are 
called  upon  to  play  their  part  in  opening  the  spikelet. 

The  pistil  present  in  the  young  staminate  flower  varies 
somewhat  in  its  method  of  development,  but  it  seldom 
proceeds  beyond  the  initial  steps  in  the  formation  of  the 
ovary  wall.  An  archesporial  cell  may  be  differentiated 
sometimes,  but  as  a  rule  this  stage  is  not  reached.  Dis- 
organization of  this  structure  begins  internally  and 
proceeds  to  such  an  extent  that  at  flowering  time  only 


109 


Figs.  io8,  109. — Cross-sections  of  a  mature  stamen.  M,  mechan- 
ical la3'er  of  cells  instrumental  in  opening  the  anther. 

a  basal  ring  of  the  epidermis  remains.  By  this  time  the 
whole  structure  is  so  inconspicuous  that  it  is  easily 
overlooked. 

In  the  pistillate  spikelet  the  only  floral  organ  to 
reach  maturity  is  the  pistil  of  the  upper  flower,  which 
develops  from  the  meristematic  region  remaining  after 
the  differentiation  of  the  stamens.  At  the  base  of  this 
rounded  protuberance,  there  arises  a  ring  of  tissue, 
which  grows  up  on  all  sides  and  arches  over  to  form  the 
wall  of  the  ovary.  The  edges  of  this  layer  of  tissue  come 
together  at  the  top,  but  they  never  unite,  and  the  small 


SPIKELETS  AND  FLOWERS  123 

stylar  canal  remains  in  the  mature  ovary.  At  the 
abaxial  side  of  the  stylar  canal  arises  a  small  protuber- 
ance, which  develops  into  the  style  and  stigma,  the  well- 
known  *'silk"  of  the  flower  (Figs.  1 10-14,  p.  124). 

A  cross-section  of  the  style  (Fig.  113)  exposes  the 
fallacy  of  the  idea  that  it  is  a  hollow  tube.  It  is  really 
a  solid,  flattened  organ  without  internal  cavity.  For 
some  distance  at  the  tip  it  is  divided  into  two  parts, 
and  the  whole  length  is  traversed  by  two  grooves  and 
two  slender,  poorly  developed  vascular  bundles. 

Pollen  tubes  usually  gain  entrance  to  the  silk  through 
the  numerous  hairs  which  give  it  its  plumose  appearance. 
Each  of  these  hairs  arises  from  an  epidermal  cell,  which 
divides  anticlinally  into  four  cells.  By  transverse 
divisions  these  give  rise  to  a  tapering  structure  consisting 
of  four  rows  of  cells  and  having  a  longitudinal  canal 
through  the  middle.  It  is  by  way  of  this  canal  that  the 
pollen  tube  usually  makes  its  way  into  the  body  of  the  silk. 

The  silk  has  evidently  originated  in  the  fusion 
laterally  of  the  two  styles  and  stigmas  of  a  primitive 
pistil  similar  to  that  of  the  other  grasses.  This  fusion 
probably  resulted  from  the  close  contact  of  the  two  struc- 
tures as  they  developed,  phylogenetically,  under  the  in- 
fluence of  the  husks  of  the  ear.  The  extraordinary  length 
of  the  silk — as  much  as  18  inches  in  some  varieties — 
is  probably  an  expression  of  an  attempt  on  the  part 
of  this  organ  to  keep  its  tip  exposed  beyond  the  envelop- 
ing leaf  sheaths.  But  the  stigmatic  portion  of  the  silk 
is  by  no  means  limited  to  the  part  exposed  beyond  the 
husks;  it  is  probable  that  all  parts  of  it  down  to  within 
an  inch  or  two  of  the  ovary  are  receptive  to  pollen. 
Growth  of  the  silk  usually  stops  as  soon  as  it  is  penetrated 


124 


THE  STORY  OF  THE  MAIZE  PLANT 


by  a  pollen  tube,  but,  if  it  be  protected  from  pollination, 
it  may  continue  to  grow  for  a  long  time. 

From  the  small  mcristematic  protuberance  remaining 
inside  the  ovar}^  after  the  development  of  the  wall  of 


Figs,  i  10-14. — Fig-  no,  tip  of  the  silk  N^ith  stigmatic  hairs.  Figs. 
Ill,  112,  segments  of  the  silk  at  some  distance  from  the  end.  Fig.  113, 
cross-section  of  the  body  of  the  silk.  Fig.  114,  pollen  grain  germinating 
on  a  stigmatic  hair. 


SPIKELETS  AND  FLOWERS  125 

the  latter,  the  ovule  develops.  Shortly  before  the 
archesporial  cell  is  differentiated,  the  two  integuments 
appear  as  rings  of  tissue  at  the  base  of  the  ovule.  By  a 
very  rapid  adaxial  growth,  the  whole  ovule  next  proceeds 
to  invert  itself,  finally  assuming  a  form  somewhere 
between  the  anatropous  and  the  campylotropous.  It  is 
attached  along  one  side  and  has  no  funiculus,  but  the 
embryo  sac  and  embryo  remain  straight.  The  outer 
integument  usually  does  not  cover  the  ovule  completely, 
its  edge  being  caught  in  the  stylar  canal  as  it  grows 
over  the  nucellus.  The  nucellus  protrudes  through  the 
large  micropyle.  The  integuments  are,  for  the  most 
part,  only  two  cells  in  thickness,  and  their  development 
stops  at  about  the  time  of  fecundation.  This  aborted 
nature  of  the  integuments  seems  to  be  characteristic  of  the 
grasses.  It  has  doubtless  arisen  as  a  correlation  with  the 
closely  investing  pericarp.  The  mature  embryo  sac  occu- 
pies a  very  small  space  at  the  abaxial  side  of  the  nucellus. 

Although  the  ovary  in  all  species  of  grasses  is  uniloc- 
ular, there  are  indications  that  the  pistil  is  composed 
of  three  carpels.^  This  is  especially  evident  in  many 
genera  often  having  three  styles;  and  in  others,  including 
maize,  it  is  shown  by  the  vascular  system.  Of  the  three 
vascular  strands  that  enter  the  base  of  the  pistil,  two 
pass  into  the  style  and  one  into  the  base  of  the  ovule. 
The  evolutionary  changes  leading  to  this  condition  have 
never  been  investigated,  but  the  tricarpellary  nature  of 
the  pistil  is  another  link  in  the  connection  between  the 
grasses  and  other  monocotyledonous  plants. 

The  abortive  stamens  at  the  base  of  the  functional 
pistil  are  dwarfed   during   development,  and   are   not 

'Walker  (144)- 


126  THE  STORY  OF  THE  MAIZE  PLANT 

distinctly  differentiated  into  anther  and  filament. 
They  make  an  effort,  however,  to  produce  pollen,  and 
the  microspore  mother-cells  are  often  differentiated 
before  disorganization  begins.  Like  the  aborted  pistil 
of  the  staminate  flower,  these  stamens  begin  to  dis- 
organize internally,  and  the  epidermis  is  the  last  to  go. 
All  that  remains  at  anthesis  is  a  basal  ring  of  the  epi- 
dermis, or  at  most,  the  minute,  shriveled  epidermal 
shell. 

In  the  lower  flower  of  the  pistillate  spikelet,  the 
stamens  meet  with  the  same  fate  as  those  of  the  upper 
flower,  and  the  pistil  shows  the  same  steps  of  development 
and  decline  as  that  in  the  staminate  flower. 


CHAPTER  XVI 


POLLINATION 

A  consistent  correlation  exists  between  structure  and 
function  of  the  parts  of  the  maize  plant  concerned  in 
pollination;  but  no  encouragement  is  offered  to  birds  or 
insects  as  agents  of  polli- 
nation. English  sparrows  I 
often  strip  the  tassels  of 
their  staminate  flowers, 
but  their  depredations 
usually  occur  before  the 
time  of  pollination.  Ants 
wander  over  the  plants, 
aimlessly,  or  looking  for 
aphids,  but  their  influence 
is  negligible.  Bees  collect 
large  quantities  of  pollen 
and  carry  it  away,  and 
many  insects  visit  the  pis- 
tillate branch  to  lay  their 
eggs  or  eat  the  silks;  but 
no  insect  seems  to  find  it 
profitable  to  visit  both 
inflorescences  at  the  right  time  to  have  any  influence  on 
pollination. 

Agencies. — Practically  the  only  agencies  actively  con- 
cerned in  the  transfer  of  pollen  are  gravity  and  the  wind, 
and  the  plant  is  well  adapted  to  these  agencies.  The 
tassel,  held  high  in  the  air,  showers  down  its  abundance 


115 


Figs.  115, 116. 
plete  pollination. 


116 


-Effects  of  incom- 


128  THE  STORY  OF  THE  MAIZE  PLANT 

of  dustlike  pollen  over  a  long  period  of  time;  and  each 
pistillate  flower,  at  a  lower  point  on  the  stem,  exposes  a 
maximum  of  stigmatic  surface  armed  with  viscid  hairs. 

The  smooth,  round  pollen  grains,  with  their  dry- 
external  surfaces,  have  a  minimum  tendency  to  stick 
to  one  another  or  to  the  leaves  and  stem  of  the  plant, 
and  they  are  easily  carried  by  the  wind. 

Although  most  of  the  pollen  of  a  single  plant  is  usually 
scattered  over  only  a  few  square  feet,  it  may,  in  a  high 
wind,  be  carried  as  much  as  a  quarter  of  a  mile. 

Duration. — A  number  of  factors  combine  to  lengthen 
the  period  during  which  the  pollen  is  being  shed  from  a 
single  inflorescence.  The  upper  flower  of  a  spikelet 
usually  reaches  maturity  a  few  days  before  the  lower, 
and  there  is  sometimes  a  noticeable  difference  in  the 
time  of  opening  of  the  sessile  and  pediceled  spikelets  of 
a  single  pair.  The  oldest  flowers  are  in  the  upper,  and 
the  youngest  in  the  lower  part  of  the  tassel.  Anthesis 
begins  at  some  distance  from  the  end  of  the  central  spike 
and  proceeds  upward  and  downward.  A  little  later,  the 
spikelets  near  the  ends  of  the  uppermost  branches  begin 
to  open,  and  a  wave  of  maturity  passes  down  all  the 
rachids  at  the  same  time.  Before  the  upper  florets  of 
the  lowest  spikelets  are  shedding  pollen,  the  lower 
florets  of  the  upper  ones  have  begun  to  open,  and  a 
second  wave  of  maturity  passes  downward.  The  flower- 
ing of  a  single  tassel  may  extend  over  a  period,  varying 
with  conditions  and  the  size  of  the  inflorescence,  from 
two  or  three  days  to  as  much  as  two  weeks  in  length. 

As  a  rule,  both  cells  of  the  anther  open  at  the  same 
time;  but,  because  of  the  limited  size  of  the  pore,  the 
poUen  is  not  all  discharged  at  once.     The  process  may 


POLLINATION  129 

require  several  hours,  but  it  is  usually  accomplished  in 
a  single  day.  The  florets  begin  to  open  soon  after 
sunrise  in  favorable  weather,  and  by  the  middle  of  the 
forenoon  the  air  in  a  field  of  flowering  corn  is  full  of 
pollen;  by  noon  most  of  the  pollen  is  shed  for  that  day. 

The  opening  of  the  floret  and  the  exsertion  of  the 
anthers  is  accomplished  very  quickly,  actual  movement 
of  the  parts  often  being  visible  under  slight  magnifica- 
tion. The  sudden  gorging  of  the  lodicules  with  water 
and  the  elongation  of  the  filaments  seem  to  be  amenable 
in  a  large  measure  to  environmental  influence,  the  opti- 
mum conditions  being  afforded  on  a  warm  forenoon  just 
following  a  rain. 

Receptivity  of  the  silk. — In  the  pistillate  inflorescence, 
as  has  been  noted,  the  oldest  flowers  are  at  the  base  and 
the  youngest  at  the  tip.  The  period  between  the 
emergence  of  the  first  and  last  silks  may  be  as  much  as 
a  week;  but,  because  of  the  greater  length  to  be  attained 
by  the  former,  this  difference  in  time  is  usually  reduced 
to  two  or  three  days.  The  silks  are  receptive  as  soon 
as  they  emerge  from  the  husks,  and  the  period  of  recep- 
tivity continues  for  two  weeks  or  more,  the  silks  con- 
tinuing to  elongate,  in  the  meantime,  if  they  are  not 
pollenized. 

Abundance  of  pollen. — In  all  wind-poUenized  plants 
much  pollen  is  \/asted,  but  ample  allowance  is  made  for 
this  in  maize.  A  single  anther  produces  about  2,500 
pollen  grains,  and  a  single  spikelet  about  15,000.  The 
staminate  spikelets  are  usually  far  more  numerous  than 
the  pistillate,  the  ratio  sometimes  being  as  great  as  10 
to  i;  and  each  pistillate  spikelet  requires  but  a  single 
pollen  grain.     The  ratio  between  supply  and  demand 


I30  THE  STORY  OF  THE  MAIZE  PLANT 

may,  therefore,  be  a  great  as  150,000  to  i;  and  a  ratio 
of  10,000  to  I  probably  occurs  in  most  varieties. 

Dichogamy. — Inflorescences  bearing  flowers  of  both 
kinds  are  definitely  protogynous,  the  silks  usually  pre- 
ceding the  pollen  long  enough  to  make  self-pollination 
within  the  inflorescence  impossible.  These  mixed  inflo- 
rescences behave,  therefore,  much  the  same  as  ordinary 
tassels  or  pistillate  units  in  pollination. 

Although  the  individual  inflorescence  is  protogynous, 
the  plant,  as  a  whole,  is  usually  protandrous,  due  to  the 
fact  that  the  tassel  is  more  advanced  in  development 
than  the  ear,  the  former  being  staminate  and  the  latter 
pistillate. 

Protandry  is  by  no  means  complete,  however,  and 
the  shedding  of  the  pollen  and  the  receptivity  of  the 
silk  usually  overlap  sufficiently  to  make  a  limited  degree 
of  self-pollination  a  thing  of  normal  occurrence,  and 
complete  self-pollination  an  experimental  possibihty. 
In  a  few  varieties  protogyny  normally  occurs  regularly. 

Significance  of  cross- pollination. — In  view  of  the 
pronounced  effects  of  inbreeding  in  maize,  the  normal 
tendencies  of  the  plant  at  the  present  time,  and  the 
conditions  to  which  it  has  been  subjected  in  the  past, 
become  significant  matters. 

Self-pollination  is  seldom  completely  prevented  by 
a  difference  in  the  time  of  maturity  of  two  inflorescences 
of  the  individual  plant;  but  cross-pollination  is  usually 
necessary  for  the  production  of  well-filled  ears,  as  is 
shown  by  the  ears  of  isolated  plants.  The  extent  of 
self-pollination,  under  normal  conditions,  cannot  be 
determined  by  the  extent  to  which  it  occurs  in  isolated 
plants,  for  a  compHcation  is  introduced  by  the  massing 


POLLINATION  131 

of  plants.  The  extent  of  self-pollination  depends  not 
upon  the  number  of  the  plant's  own  pollen  grains  that 
ultimately  reach  its  silks,  but  upon  the  number  that  get 
there  ahead  of  all  others. 

The  meager  data  now  at  hand  indicate  that,  under 
ordinary  field  conditions,  where  the  plants  are  grown 
in  clumps  of  three  or  four,  self-pollination  occurs  in 
only  about  5  per  cent  to  10  per  cent  of  the  seeds.  All 
that  we  know  of  the  agriculture  of  the  Indians  indicates 
that  the  growing  of  corn  in  hills  has  been  practiced  for 
centuries  by  practically  all  tribes  of  both  continents. 
The  hmitations  of  the  aboriginal  methods  of  cultivation 
made  this  a  profitable  method  of  planting,  and  the 
number  of  plants  grown  in  a  hill  was  often  as  high  as 
ten  or  twelve.  This  massing  of  plants  was  a  decided 
encouragement  to  cross-pollination,  and  the  selective 
effect  of  this  condition  has  probably  been  the  active 
factor  concerned  in  the  development  of  the  intolerance 
of  self-fertilization. 


CHAPTER  XVII 
GAMETOGENESIS  AND  FECUNDATION 

At  flowering  time  of  the  maize  plant,  a  striking 
picture  is  presented  by  the  expanded  tassel,  releasing 
its  shower  of  pollen  to  be  received  by  the  conspicuous 
tuft  of  silks  below.  But  these  readily  visible  features 
are  merely  accessory  to  certain  fundamental  processes 
revealed  only  now  and  then  under  high  magnification 
and  in  response  to  special  technique. 

The  pollen  grain  that  falls  on  a  silk  has  had  a  signifi- 
cant past  and  is  to  have  a  short  but  active  future;  and 
the  silk  itself  leads  the  way  down  to  the  culmination  of 
one  of  the  most  peculiar  occurrences  of  cellular  activity 
known  anywhere  in  the  kingdom  of  living  things.  The 
end  of  the  whole  process  seems  to  be  the  production  of 
certain  sexual  cells  and  the  methodical  union  of  these 
cells  to  form  the  beginnings  of  a  seed,  the  forerunner  of 
a  new  generation  of  the  plant. 

Each  pollen  grain  is  to  produce  two  sperms,  together 
with  the  apparatus  for  conducting  them  to  the  ovule 
and  into  the  presence  of  two  other  cells  of  gametic 
nature.  One  of  these,  the  egg,  is  definitely  female; 
but  the  other,  the  endosperm  cell,  is  of  doubtful  nature 
sexually.  In  the  union  of  one  sperm  with  the  egg  is 
the  origin  of  the  embryo  of  the  seed,  and  the  endosperm 
arises  from  the  fusion  of  the  other  sperm  with  the 
endosperm  cell. 

The  details  of  the  events  leading  to  the  formation 
of  the  gametes  and  to  their  union  in  fecundation  are  of 
132 


GAMETOGENESIS  AND  FECUNDATION  133 

great  theoretical  importance  in  all  organisms;  but 
certain  consequent  hereditary  phenomena,  which  find 
their  most  significant  expression  in  maize,  render  the 
process  unusually  interesting  in  this  plant. 

TJie  pollen  grain. — Early  in  the  development  of  the 
anther,  the  four  sporangia  are  differentiated,  each 
containing  its  long  column  of  sporogenous  tissue  sur- 
rounded by  tapetal  layers.  A  time  soon  comes  when  the 
sporogenous  cells  cease  to  divide  in  the  ordinary  way, 
but  they  continue  to  grow  rapidly  at  the  expense  of 
the  surrounding  tapetum.  These  become  the  pollen 
mother-cells. 

The  heterotypic  division  takes  place  quickly,  and 
the  small,  short  chromosomes  are  observed  with  difficulty 
in  the  dense  cytoplasm.  Even  the  number  of  chromo- 
somes is  a  matter  of  some  doubt.  The  most  extensive 
observations  that  have  been  made  on  this  point  indicate 
a  variable  number,  with  ten  predominating  in  the  starchy 
varieties  and  twelve  in  the  sweet  varieties  as  the  haploid 
number.  But  accompanying  these  apparent  variations 
in  number  is  a  variation  in  the  size  of  the  chromosomes; 
and  this,  together  with  the  difficulty  of  observation  and 
the  uncertainty  in  distinguishing  large  chromosomes 
from  groups  of  smaller  ones,  leaves  the  actual  variation 
in  number  open  to  question.  The  results  obtained  in 
attempts  to  count  the  diploid  number  in  vegetative 
cells  have  been  little  more  satisfactory.  Here  the 
chromosomes  are  long  and  twisted  and  indistinct.  The 
relative  instability  of  varieties  of  maize,  and  the  lack  of 
consistently  correlated  differences  between  sweet  and 
starchy  varieties,  makes  it  essential  that  the  fact  of  a 
consistent  difference  in  the  number  of  chromosomes  be 


134  THE  STORY  OF  THE  MAIZE  PLANT 

firmly  established  before  it  be  made  the  basis  of  any 
extended  theoretical  consideration. 

Immediately  following  the  reduction  division,  the 
two  daughter-cells  divide  homotypically,  and  the  four 
cells  of  the  tetrad  round  off  and  proceed  to  mature  into 
pollen  grains.  Two  more  nuclear  divisions  occur,  and 
a  thick  wall  with  a  conspicuous  germ  pore  is  formed, 
before  the  pollen  grain  is  ready  to  leave  the  anther. 
The  details  of  these  latter  steps  in  maturation  have 
never  been  observed. 

At  maturity  the  pollen  grain  is  almost  spherical, 
but  this  shape  is  sometimes  modified  by  the  effect  of 
pressure  of  other  spores  during  development,  and  by 
shrinkage  due  to  desiccation.  The  thick  exine  is 
minutely  tuberculate.  The  intine  is  thin  except  for  a 
ring  around  the  germ  pore.  The  cytoplasm  is  so  dense 
as  to  make  observation  of  other  contents  of  the  spore 
very  difficult.  The  vegetative  nucleus  is  poorly  organ- 
ized (Fig.  1 1 8). 

At  the  time  of  leaving  the  anther  the  mature  pollen 
grain  contains  the  fully  developed  sperms.'  These  are 
two  small,  crescent-shaped  cells  with  long  attenuate 
ends.  The  nucleus,  which  seems  to  be  a  compact 
mass  of  chromatin,  constitutes  the  greater  part  of  the 
sperm. 

The  pollen  tube. — The  pollen  grain  of  maize  has  the 
task  of  producing  one  of  the  longest  pollen  tubes  known 
in  the  plant  kingdom.  For  this  it  is  provided  with  a  rich 
store  of  food,  later  to  be  supplemented  by  a  supply 

'  Some  authorities  state  that  the  sperms  are  not  formed  until  after 
the  emergence  of  the  pollen  tube,  but  improved  technique  shows  this 
idea  to  be  incorrect.     See  Andronescu  (3). 


GAMETOGENESIS  AND  FECUNDATION  135 

drawn  from  the  style  upon  which  it  feeds.  In  their 
compact  structure,  the  sperms  are  well  adapted  to  their 
long  journey  from  the  pollen  grain  to  the  embryo  sac. 

Pollen  grains  may  be  germinated  in  various  nutrient 
media,  but  their  normal  behavior  is  readily  observed 
while  they  are  growing  on  the  silk.  The  stigmatic 
hairs  of  the  silk  are  apparently  covered  with  a  viscous 
substance  which  holds  the  pollen  grains  and  probably 
stimulates  them  to  the  first  steps  of  germination.  Under 
favorable  conditions,  germination  may  begin  and  the 
pollen  tube  become  well  established  in  the  silk  in  as 
short  a  time  as  two  hours. 

The  tube  emerges  from  the  pollen  grain  by  way  of 
the  germ  pore  and  usually  enters  the  silk  through  one 
of  the  hairs  of  the  stigma  (Fig.  114,  p.  124).  It  may, 
however,  enter  the  body  of  the  silk  directly.  Once  inside, 
it  makes  its  way  through  the  parenchyma  to  one  of  the 
vascular  bundles,  from  whose  richly  stored  sheathing 
elements  it  absorbs  nourishment  as  it  proceeds  toward 
the  ovule.  Growing  at  one  end  and  dying  at  the  other, 
the  tube  makes  its  way  downward;  and,  although  the 
total  distance  trasversed  may  be  considerably  more 
than  a  foot,  probably  much  less  than  an  inch  of  the 
tube  is  ever  really  alive  at  any  one  time.  Its  growth  is 
so  rapid  that,  under  favorable  conditions  of  temperature 
and  humidity,  fecundation  follows  pollination  within 
twenty-four  to  thirty-six  hours. 

It  is  a  well-known  fact  that  the  period  of  pollination 
constitutes  a  critical  phase  in  the  Kfe-cycle  of  the  plant. 
Many  Indian  tribes  in  prehistoric  times  had  elaborate 
religious  ceremonies  designed  to  bring  the  crop  through 
this  crisis,  and  the  observant  farmer  well  knows  that  his 


136  THE  STORY  OF  THE  ]\IAIZE  PLANT 

crop  is  often  made  or  lost  1j}-  a  warm  shower  or  a  few  hot, 
dry  days  when  the  corn  is  in  silk.  This  critical  period 
is  probably  attendant  upon  the  germination  of  the 
pollen  grain  and  the  establishment  of  the  tube  in  contact 
with  a  permanent  supply  of  moisture  in  the  silk. 
Although  the  tube  is  exposed  to  the  air  for  only  a  few 
minutes  while  passing  from  the  pollen  grain  to  the 
stigmatic  hair  of  the  silk,  yet  its  diminutive  size  and 
delicate  structure  render  it  very  susceptible  to  desic- 
cation; and  this  step  in  the  process  usually  takes  place 
during  the  warmest  part  of  the  day.  The  pollen  grain 
itself,  being  viable  for  only  a  day  or  two,  under  the  best 
of  conditions,  is  susceptible  to  injury  from  this  same 
cause;  but  the  importance  of  this  factor  is  minimized 
by  the  short  time  required  on  the  very  direct  route  from 
the  anther  to  the  stigma. 

The  pollen  tube  has  no  fixed  pathway  after  reaching 
the  ovary.  It  seems  certain  that  it  does  not,  as  some 
have  supposed,  leave  the  body  of  the  style  to  enter  the 
ovary  by  way  of  the  stylar  canal.  It  usually  follows  the 
vascular  tissue  well  down  along  the  side  of  the  ovary 
before  entering  the  ovarian  cavity.  Entering  the  ovule 
by  way  of  the  micropyle,  it  crowds  its  way  between  the 
cells  of  the  nucellus  and  empties  its  contents  into  the 
embryo  sac  near  the  egg  (Fig.  120). 

The  megaspore  and  embryo  sac. — Soon  after  the 
appearance  of  the  integuments  of  the  developing  ovule, 
the  archesporial  cell  is  differentiated  just  beneath  the 
epidermis  of  the  young  nucellus.  By  a  pericHnal 
division,  this  cell  gives  rise  to  an  outer  tapetal  cell  and 
an  inner  megaspore  mother-cell.  The  former  is  immedi- 
ately absorbed  by  the  latter,  which  undergoes  a  period 


GAMETOGENESIS  AND  FECUNDATION  137 


Figs  117  2. — I  1^  117,  miture  cmbrvo  sac.  Fig.  118,  section  of 
m;iture  jwUcn  grain.  1  ig  119,  sperm,  l^ig.  120,  entrance  of  pollen 
tube  into  embryo  sac.  Fig.  121,  fecundation  of  the  egg.  Fig.  122, 
fecundation  of  the  endosperm  nucleus.  0,  outer  integument;  i,  inner 
integument;  t,  pollen  tube;  w,  wall  of  the  ovary;  s,  sperm;  n,  vege- 
tative nucleus  of  pollen  tube;    e,  egg;    p,  polar  nuclei;   s,  synergid. 


138  THE  STORY  OF  THE  MAIZE  PLANT 

of  growth  before  dividing  again.  The  parietal  layer  of 
tissue,  several  cells  in  thickness,  which  finally  separates 
the  embryo  sac  from  the  epidermis,  is  produced  from 
epidermal  cells  by  pericHnal  divisions. 

Following  the  heterotypic  division  of  the  nucleus 
of  the  megaspore  mother-cell,  a  wall  is  laid  down  dividing 
the  cell.  By  a  homot}^ic  division,  the  inner  one  of 
these  cells  divides  again,  producing  two  megaspores. 
The  outer  one  also  begins  to  divide,  but  this  act  is 
usually  arrested  by  the  beginning  of  a  process  of  dis- 
organization, which  soon  includes  the  adjacent  mega- 
spore, leaving  only  the  more  deeply  seated  megaspore. 

The  persistent  megaspore  now  enlarges,  absorbing 
the  disorganizing  sporogenous  cells  and  the  surrounding 
tissue  of  the  nucellus.  At  the  same  time  the  nucleus 
begins  a  definite  series  of  divisions,  resulting  finally  in 
eight  nuclei.  The  two  nuclei  produced  by  the  first  division 
move  to  opposite  ends  of  the  enlarging  cell,  and  each 
divides  again.  One  of  the  new  nuclei  at  the  micropylar 
end  of  the  cell  next  divides,  forming  the  nuclei  of  the 
two  synergids;  and  the  other  divides  to  form  the  egg 
nucleus  and  one  polar  nucleus.  Meanwhile,  at  the  other 
end  of  the  developing  embryo  sac,  one  nucleus  has 
divided  to  form  two  antipodal  nuclei,  and  the  other  to 
form  one  antipodal  and  one  polar  nucleus. 

When  these  divisions  are  completed  and  eight  nuclei 
are  present,  membranes  are  formed,  cutting  off  the  cells 
of  the  egg  apparatus.  At  the  same  time,  the  walls  of 
the  antipodal  cells  are  formed,  and  the  two  polar  nuclei 
approach  each  other  in  the  large  cavity  of  the  endosperm 
cell.  Their  actual  fusion  is  delayed,  however,  until 
the  time  of  fecundation. 


GAMETOGENESIS  AND  FECUNDATION  139 

As  in  other  grasses,  the  antipodal  cells  begin  vegetative 
division  as  soon  as  they  are  formed,  and  fifty  or  more  may 
be  present  when  the  embryo  sac  is  mature  (Fig.  117). 

Development  of  the  pistil. — Although  the  developing 
embryo  sac  has  increased  greatly  in  size,  both  before  and 
after  its  organization,  it  has  not  kept  pace  with  the 
nucellus;  and  at  maturity  it  occupies  only  a  small  part 
of  the  interior  of  the  ovule.  It  is  not  until  the  embryo 
sac  has  completed  its  development  that  the  style  and 
stigma  have  made  sufficient  development  to  be  partly 
exposed  beyond  the  husks  and  ready  for  pollination. 

Fecundation. — The  entrance  of  the  pollen  tube  into 
the  embryo  sac  usually  destroys  one  or  both  synergids, 
and  in  the  resulting  cytoplasmic  confusion  the  sperms 
are  followed  with  difficulty.  It  has  long  been  accepted 
as  a  fact  that  one  sperm  unites  with  the  egg  to  form  the 
forerunner  of  the  embryo;  and,  because  of  its  genetic 
importance  in  connection  with  the  occurrence  of  xenia, 
the  fate  of  the  other  sperm  has  been  a  matter  of  con- 
siderable interest  since  the  discovery  of  "double  fecunda- 
tion" in  some  other  plants.  It  has  now  been  fully 
demonstrated  that  this  sperm  unites  with  the  two  polar 
nuclei,  giving  rise  to  the  endosperm  of  the  seed.' 

The  significance  of  this  sexual,  or  pseudo-sexual, 
origin  of  the  endosperm,  which  seems  to  be  of  common 
occurrence  among  the  angiosperms,  is  a  morphological 
mystery.  What  the  general  interpretation  of  the 
phenomenon  is,  and  how  maize  elucidates  and  yet 
complicates  the  problem,  will  be  brought  out  in  a  later 
discussion  of  heredity  in  the  endosperm.- 

'Lee  Guignard  (70),  Weatherwax  (154),  and  Miller  (109). 
^  See  chap,  xxiii. 


CHAPTER  XVm 

THE  FRUIT 

The  loose  definition  of  the  word  fruit  permits  its 
application  to  either  the  ear  or  the  individual  grain  of 
maize.  In  the  strictest  sense,  the  grain  is  the  fruit,  for 
it  is  the  structure  developed  from  the  ovary  as  a  result 
of  fecundation.  But  the  compact  nature  of  the  ear, 
which  is  a  matured  inflorescence,  makes  it  convenient, 
and  entirely  consistent  with  recognized  terminology, 
to  call  it  a  multiple  fruit.' 

Many  details  of  the  ear  are  inseparable  from  those  of  the 
pistillate  inflorescence  and  have  been  treated  in  an  earlier 
description.^  The  ear  is  characterized  by  as  great  a  range 
of  variation  as  is  shown  in  other  parts  of  the  plant,  and 
this  variability  is  the  basis  upon  which  the  improvement 
of  agricultural  varieties  has  usually  been  accomplished. 

Structure. — The  axis  of  the  ear  is  commonly  called 
the  coh.^  It  has  the  essential  characteristics  of  a  sec- 
tion of  the  stem,  but  its  nodes  are  so  close  together  that 
the  identity  of  the  internodes  is  lost.  The  central  por- 
tion of  the  cob  is  a  soft,  white  pith  without  vascular 
bundles,  the  latter  being  located  in  the  peripheral  layer 
of  hard,  woody  sclerenchyma.  The  chaffy  covering  is 
made  up  of  the  bracts  of  the  spikelets. 

'  Technically  most  like  a  sorosis,  although  the  axis  is  not  succulent 
as  in  the  typical  sorosis. 

2  See  chap.  xiv. 

3  By  analogy  the  word  coh  would  be  correctly  applied  to  the  whole 
fruit,  and  European  writers  so  employ  it.  But  usage  in  America  is  as  here 
indicated. 


THE  FRUIT  141 

The  grains  are  so  arranged  on  the  cob  that  the  embryo 
of  each  is  turned  toward  the  tip  of  the  ear.  Because  of 
the  pecuHar  nature  of  the  pistillate  spikelet,  half  of  the 
grains  on  an  ear  of  Country  Gentleman  sweet  corn  are 
usually  turned  so  that  the  embryos  face  the  base  of  the 
ear,  and  an  occasional  grain  in  any  ear  may  be  so  turned. 

The  number  of  rows  of  grains  varies  from  four  to 
thirty  or  more.  The  constantly  even  number  of  rows 
is  explained  by  the  fact  that  the  structural  unit  is  a  pair 
of  rows  borne  in  a  row  of  paired  spikelets  (Figs.  76,  77, 
p.  104) .  The  discontinuance  of  one  or  more  of  these  rows 
of  pairs  is  responsible  for  occasional  differences  of  two, 
four,  or  even  more  rows  between  the  tip  and  the  base  of 
the  ear.  Four-rowed  ears  are  rare;  six-rowed  ears  have 
never  been  known  to  occur;  and  eight  is  the  smallest 
number  of  rows  commonly  encountered. 

Size  and  shape. — Ears  range  in  length  from  i  inch, 
in  some  of  the  South  American  pop  varieties,  to  20 
inches,  in  some  of  the  more  vigorous  flints  and  dents. 
The  absence  of  any  consistent  correlation  between  length 
and  diameter  makes  possible  a  multitude  of  shapes. 
There  is  a  natural  tendency  for  the  ear  to  taper  gradually 
from  the  base  to  the  tip,  due  to  a  progressive  decrease 
in  the  size  of  the  cob  and  the  grains,  to  closer  crowding, 
or  to  the  loss  of  two  or  more  rows.  Some  of  the  short, 
conical  ears  of  varieties  grown  in  the  Andes  are  borne 
in  pistillate  branches  wholly  out  of  proportion  to  the 
diminutive  size  of  the  ear.  (Some  types  of  ears  are 
shown  in  Figs.  123-34.) 

Show  corn. — Dent  corn  is  the  standard  type  through- 
out the  Corn  Belt.  The  ideal  ear  has  been  agreed  upon 
by  growers,  and  the  judging  of  show  ears  has  been 


142 


THE  STORY  OF  THE  MAIZE  PLANT 


developed  to  a  high  degree  of  accuracy.  The  production 
of  the  ear  or  ten-ear  exhibit  that  is  awarded  a  state 
championship  is  no  insignificant  achievement;  and  the 
national  championship,  which  is  conceded  to  be  the 
world-championship,  is  a  coal  too  mean  for  the  aim  of  none. 


Figs.  123-27. — Ears  of  the  endosperm  varieties,  soft,  flint,  dent, 
pop,  and  sweet,  respectively. 


The  ideal  ear  of  dent  corn  is  from  8  to  10  inches  in 
length,  depending  upon  the  variety  and  the  section  in 
which  it  is  grown.  Its  greatest  circumference,  which  is 
near  the  middle,  is  three-fourths  the  length;  from  this 
it  tapers  very  slightly  to  the  base,  and  a  little  more  to 
the  tip.  The  base  and  tip  are  well  filled  with  grains  of 
good  size  and  shape.  A  swollen  base  with  a  large  area 
of  attachment  to  the  shank  is  undesirable.  A  pro- 
nounced conical  shape,  or  a  short  portion  of  unfilled 


THE  FRUIT 


143 


cob  at  the   tip,  is  sufl&cient  for  disqualification.     The 
number  of  rows  is  from  18  to  24;  these  must  be  straight 


Figs.  128-34. — Figs.  128,  129,  ears  of  varieties  common  on  the 
western  slope  of  the  Andes.  Fig.  130,  a  conical  type  of  ear  grown  in 
many  places  where  careful  breeding  is  not  practiced.  Fig.  131,  type  of 
what  was  probably  the  best  dent  com  grown  in  America  in  pre-Columbian 
times.  Fig.  132,  short,  thick  ear  of  a  pop  variety.  See  also  Fig.  71. 
Figs.  133,  134,  pod  corn 

and  uniform,  and  must  continue  for  the  full  length  of 
the  ear. 

The  depth  of  the  grain  is  dependent  in  a  measure 
upon  the  variety,  but  the  weight  of  the  shelled  grain  is 
about  four-fifths  that  of  the  whole  ear.     The  dent  in 


144  THE  STORY  OF  THE  MAIZE  PLANT 

the  grain  must  be  characteristic,  any  tendency  toward 
a  glassy  smoothness  being  especially  undesirable. 

The  grains  must  be  clear  and  uniform  in  color. 
Grains  off  color  because  of  mixture  with  other  varieties 
count  off  heavily  in  scoring.  The  cob  must  be  white 
in  white  varieties,  and  bright  red  in  yellow  varieties. 


Fig.  135. — A  prize-winning  exhibit  of  dent  corn.  (These  ten  ears 
were  awarded  grand  sweepstakes  in  a  field  open  to  the  world,  at  the 
International  Grain  and  Hay  Show,  at  Chicago,  1920.  Grown  by 
C.  E.  Troyer,  La  Fontaine,  Indiana.  Photograph  by  courtesy  of 
A.  F.  Troyer.) 

Special  classes  are  sometimes  provided  for  mixed  varie- 
ties and  for  a  widely  distributed  white  variety  having  a 
red  cob. 

Some  dent  varieties  varying  widely  from  these  specifi- 
cations are  extensively  grown;  but  they,  hke  other 
varieties  than  dent,  seldom  enter  the  show  ring  in  the 
Corn  Belt  except  under  special  conditions. 

Pod  corn. — As  an  agricultural  curiosity  without 
economic  value,  pod  corn  is  grown  occasionally  by 
students  of  the  plant  all  over  the  world.     In  this  variety 


THE  FRUIT  145 

the  bracts  of  the  pistillate  spikelet  are  so  well  developed 
that  they  form  a  tiny  husk  covering  each  grain  (Figs. 
133,  134).  The  whole  ear  is  also  covered  by  the  normal 
husks. 

Pod  corn  is  not  a  variety  distinct  from  all  others. 
The  character  of  its  grains  makes  it  amenable  to  classifi- 
cation among  the  dent,  flint,  pop,  sweet,  or  soft  varie- 
ties; and  its  other  characteristics  are  as  little  its  own 
exclusively,  with  the  possible  exception  of  the  tendency 
to  bear  pistils  in  its  tassels. 

The  caryopsis. — A  grain  of  corn  is  an  object  of  very 
great  interest  both  economically  and  theoretically. 
Affording  the  largest  and  most  easily  dissected  speci- 
men of  the  caryopsis,  the  characteristic  fruit  of  the 
grasses,  it  is  much  used  for  illustrative  purposes  in 
textbooks.  The  variability  and  peculiar  origin  of  the 
endosperm  of  its  single  seed  introduce  complicated  prob- 
lems of  heredity  that  have  given  the  plant  a  prominent 
place  in  the  research  of  the  last  two  decades.  As  the 
storehouse  of  most  of  the  food  elaborated  by  the  plant 
during  its  life,  the  fruit  is  the  key  to  the  important 
role  that  maize  has  played,  and  is  still  playing  with  daily 
increasing  importance,  in  the  economic  life  of  humanity. 
Modern  milling  processes  and  feeding  practices  are 
carried  on  with  a  success  proportionate  to  the  account 
that  is  taken  of  the  physical  structure  and  chemical 
composition  of  the  various  parts  of  the  caryopsis. 

As  has  previously  been  stated,  a  grain  of  corn  con- 
sists of  three  essential  parts.  The  part  for  which  all  the 
rest  of  the  grain  exists  is  the  embryo — the  young  corn 
plant  in  a  dormant  condition.  This  consists  of  a  bud,  a 
lateral  cotyledon,  and  the  primordium  of  a  root.     The 


146  THE  STORY  OF  THE  MAIZE  PLANT 

embryo  is  embedded  in  the  side  of  the  endosperm,  a 
mass  of  tissue  rich  in  proteins  and  carbohydrates.  Sur- 
rounding both  of  these  parts  is  a  tough,  fibrous  hull, 
consisting  of  the  testa  and  the  pericarp. 

The  role  of  these  parts  in  germination  has  already 
been  described,  but  they  have  had  a  past,  even  as  they 
are  to  have  a  future,  and  this  will  now  be  taken  up  in 
some  detail. 


CHAPTER  XIX 

THE  EMBRYO 

When  the  identity  of  the  sperm  has  been  lost  in  the 
egg,  fecundation  may  be  said  to  have  been  completed 
and  the  embryonic  life  of  the  new  individual  to  have 
begun.  The  young  zygote  resembles  so  closely  an 
unfertilized  egg  that  the  two  are  distinguishable  only 
with  the  aid  of  secondary  evidences  of  fecundation, 
such  as  the  presence  of  remnants  of  a  pollen  tube,  the 
destruction  of  the  synergids,  or  the  beginning  of  division 
in  the  endosperm  cell. 

The  young  embryo  develops  slowly.  Several  hours 
after  fecundation,  the  fertihzed  egg  cell  is  divided  by  a 
transverse  wall  into  two  very  unequal  cells.  The 
smaller,  which  has  a  very  dense  cytoplasm,  is  to  develop 
into  the  persistent  parts  of  the  embryo.  The  larger, 
whose  cytoplasm  is  vacuolate,  is  the  forerunner  of 
the  suspensor,  the  rapidly  growing,  temporary  struc- 
ture that  forces  the  developing  embryo  into  the  endo- 
sperm. 

Differentiation. — Symmetrical  developmisnt  of  the 
body  of  the  embryo  ensues  for  only  a  short  time  before 
the  cotyledon  begins  to  differentiate  as  a  lateral  lobe. 
When  this  structure  has  developed  far  enough  that  its 
lateral  position  is  evident,  the  plumule  arises  in  a  morpho- 
logically terminal  position  (Figs.  136-42).  The  cole- 
optile,  which  is  the  first  part  of  the  plumule  to  appear, 
arises  as  an  open  sheath,  whose  edges  are  later  completely 
united.  Inside  of  this  sheath,  the  primordia  of  several 
147 


THE  STORY  OF  THE  MAIZE  PLANT 


foliage  leaves,  and  sometimes  one  or  more  axillary  buds, 
are  developed  before  the  maturity  of  the  seed. 

Next  in  order,  the  cylindrical  primary  root  is  split 
out  of  the  body  of  the  axis  of  the  embryo,  between  the 
plumule  and  the  suspensor.  From  the  tissue  left 
surrounding  the  root  proper,  the  root  cap  is  later  split 


145    Rs 


Figs.  136-45. — Figs.  136-41,  longitudinal  sections  showing  devel- 
opment of  the  embryo.  Fig.  142,  longitudinal  section  of  mature  embryo. 
Figs.  143-45,  transverse  sections  of  mature  embryo  through  different 
regions.  C,  cotyledon;  S,  suspensor;  P,  plumule;  R,  root;  Ps,  plumule 
sheath  (coleoptUe) ;  Rs,  root  sheath  (coleorhiza) ;  Re,  root  cap;  E,  meri- 
stematic  rudiment  of  a  second  cotyledon. 

off,  and  the  remaining  sheathing  portion  constitutes  the 
coleorhiza.  Three  or  more  secondary  roots  are  later 
differentiated  from  the  central  cylinder  of  the  axis  of 
the  embryo,  near  the  point  of  attachment  of  the  coty- 
ledon, and  from  the  cortex  a  cap  is  split  off  for  each  root 
and  carried  outward  on  the  end  of  the  latter  at  the  time 
of  germination  of  the  seed. 


THE  EMBRYO  149 

Meanwhile  the  suspensor  has  developed  to  several 
cells  in  thickness  and  has  kept  increasing  in  length 
fast  enough  to  keep  the  cotyledon  at  all  times  well  in 
contact  with  the  endosperm.  The  pressure  exerted  by 
the  growth  of  the  suspensor  is  great,  as  is  often  shown 
by  its  contorted  shape  (Fig.  140).  Almost  opposite  the 
cotyledon  there  is  often  seen  a  region  of  embryonic 
tissue,  which  is  doubtless  the  equivalent  of  the  epiblast 
of  some  other  grasses.  This  is  evidently  the  rudiment 
of  another  cotyledon. 

Pseudo-polyemhryony. — Actual  polyembryony  has 
never  been  reported  in  maize.  The  appearance  of  this 
phenomenon,  in  rare  instances,  is  due  to  the  dupHcation 
of  the  central  axis-of  the  embryo,  resulting  in  the  produc- 
tion of  two,  or  very  rarely  three,  plants  by  only  one  seed. 
The  infrequent  occurrence  of  this  anomaly  seldom  gives 
a  botanist  opportunity  for  examining  such  material, 
and  cases  of  true  polyembryony  may  yet  be  discovered. 

Nodes  of  the  embryonal  axis. — Notwithstanding  some 
opinions  to  the  contrary,  the  embryo  affords  very  suggest- 
ive evidence  of  a  previous  dicotyledonous  condition. 
The  functional  cotyledon  is  apparently  located  at  the 
first  node  of  the  plant,  the  rudimentary  cotyledon  at 
the  second,  the  coleoptile  at  the  third,  and  the  first 
fohage  leaf  at  the  fourth. 


CHAPTER  XX 

THE  SEED  COAT 

The  protective  covering  of  the  grain  of  corn  consists 
of  the  testa  and  the  pericarp.  The  former  is  the  remnant 
of  the  integuments  of  the  ovule;  the  latter  is  the  wall 
of  the  matured  ovary. 

The  part  played  by  the  integuments  is  apparently  of 
little  importance,  and  they  are  never  very  well  developed. 
After  fecundation,  they  degenerate  and  are  ultimately 
crushed  to  a  thin,  disorganized  layer  by  the  growth  of 
other  parts  of  the  fruit. 

Development  of  the  pericarp. — During  the  initial  steps 
in  the  formation  of  the  embryo,  the  cells  of  the  ovary 
wall  continue  to  divide  and  increase  in  size.  As  the 
fruit  nears  maturity,  these  cells  cease  to  divide,  and  their 
walls  begin  to  thicken.  Increase  in  size  of  the  pericarp 
from  this  time  forward  is  accomplished  by  the  stretching 
of  the  tissues  already  formed.  Its  tardy  development, 
at  all  stages,  keeps  it  in  a  constant  state  of  tension  and 
gives  it  its  tough,  fibrous  nature  in  the  mature  form. 
The  tension  at  maturity  is  often  great  enough  to  cause 
the  pericarp  to  split  and  the  endosperm  to  protrude. 

Layers  of  the  pericarp. — The  subepidermal  portion  of 
the  pericarp  consists  of  two  rather  definitely  separated 
layers.  These  are  much  the  same  in  structure,  except  in 
the  region  of  the  point  of  attachment  of  the  grain.  Here 
the  outer  layer  is  histologically  modified  as  it  continues 
downward,  forming  the  spongy  pedicel  of  the  fruit. 
The  inner  layer  becomes  densely  pigmented  with  brown 


THE  SEED  COAT  151 

or  black  just  opposite  the  end  of  the  scutellum  as  the 
fruit  approaches  maturity. 

This  pigmented  spot  is  present  in  all  varieties  of 
maize,  as  well  as  in  many  other  grasses.  The  two 
layers  of  the  pericarp  seem  to  be  loosely  held  together 
opposite  this  pigmented  area,  which  is  easily  exposed 
by  breaking  off  the  pedicel  of  the  grain.  Grains  that 
are  diseased,  or  improperly  matured,  often  break  off  at 
this  surface  on  being  merely  shelled  from  the  cob,  this 
occurrence  giving  rise  to  the  common  impression  that 
the  black  spot  is  an  abnormal  thing,  the  result  of  disease. 
But  the  spot  itself  is  normal;  it  is  only  its  revelation 
under  these  conditions  that  is  an  indication  of  an 
abnormal  physiological  condition. 

Color. — The  color  of  the  pericarp  may  be  a  light  yellow 
or  cream,  but  it  is  seldom,  if  ever,  a  pure  white.  A 
pericarp,  seeming  to  be  white  when  underlaid  with  a 
white,  floury  endosperm,  will  show  a  decided  tint  when 
seen  against  a  background  of  corneous  white  endosperm. 
From  these  lighter  tints,  different  varieties  show  all 
gradations  through  yellow  or  orange  to  a  dark  brown, 
and  through  pinks  and  reds  to  a  very  deep  red.  (Plate  II 
Figs.  I,  2.) 

As  a  rule,  the  pericarps  of  all  the  grains  of  any  one 
ear,  being  genetically  alike,  are  alike  in  color;  but  this 
is  by  no  means  true  of  the  endosperms  of  all  the  grains 
of  the  ear.  Segregation  of  hereditary  factors  preceding 
the  formation  of  the  latter,  and  the  chances  for  xenia 
through  cross-pollination,  make  it  possible  for  all  the 
primary  colors  of  endosperm  to  occur  on  one  ear. 

The  general  uniformity  of  pericarp  color  renders  an 
occasional  red  ear  in  a  white  variety  a  conspicuous  object, 


152  THE  STORY  OF  THE  MAIZE  PLANT 

and  has  well  fitted  it  for  the  unique  part  that  it  played 
in  the  husking  bees  of  days  gone  by.' 

An  exception  occurs  in  an  occasional  red  ear  with 
both  red  and  white  grains  showing  various  patterns  of 
distribution  and  having  the  pigment  in  the  pericarp. 
The  striping  of  individual  grains  with  red  and  white  also 
occurs  regularly  in  some  varieties.     (Plate  II,  Figs.  3,4.) 

In  some  varieties  the  pericarp  color,  usually  red, 
fails  to  develop  unless  the  grains  are  exposed  to  light 
during  maturity.  The  "smut  nose"  variety  of  flint 
corn  grown  in  some  sections  is  one  of  these  in  which  the 
tip  of  the  ear,  protruding  beyond  the  ends  of  the  husks, 
develops  the  characteristic  color,  while  the  protected 
portion  remains  white.^ 

^  See  p.  219,  note. 

2  Blakeslee  (7)  and  others  have  succeeded  in  printing  on  such  ears 
photographically,  using  as  the  negative  a  piece  of  tin  foil  cut  out  in 
simple  designs.  A  portion  of  the  husk  is  removed  from  an  immature 
ear  and  the  negative  placed  over  the  grains  and  left  there  until  the  ear  is 
mature,  the  pigment  developing  in  the  areas  exposed  to  the  light. 


CHAPTER  XXI 
THE  ENDOSPERM 

In  the  endosperm  of  maize,  as  of  all  the  cereals,  lies 
its  chief  economic  importance.  From  the  standpoint  of 
the  miller,  the  canner^  and  the  feeder,  the  characteristics 
and  possibihties  of  this  tissue  are  well  understood;  and 
the  primary  division  of  the  species  into  agricultural 
varieties  is  usually  based  upon  the  endosperm.  But 
botanically,  also,  the  endosperm  of  maize  is  of  extreme 
importance,  being  subject  to  all  the  uncertainty  of 
interpretation  that  characterizes  the  endosperm  of 
angiosperms  in  general. 

Theoretical  significance. — Some  prefer  to  consider  the 
endosperm  of  angiosperms  merely  a  nurse  tissue  for 
converting  the  nucellus  into  nutriment  suitable  for  the 
embryo;  but  such  an  interpretation  does  not  give  due 
emphasis  to  the  suggestion  of  sexuality  in  its  origin. 
The  very  general  participation  of  one  of  the  sperms  of 
the  pollen  tube  in  the  formation  of  the  endosperm 
doubtless  has  a  phylogenetic  significance  that  is  over- 
looked in  this  purely  physiological  interpretation.  To 
those  who  have  looked  at  the  problem  from  the  morpho- 
logical point  of  view  in  recent  years,  the  endosperm 
seems  to  have  a  sexual  origin,  and  to  be  in  reality 
a  distinct  individual — the  embryo's  sister-and-a-half. 
It  has  a  distinct  ontogeny,  and  shows  a  high  degree 
of  differentiation  in  the  adult  form.  It  is  peculiar  in 
its  triple  origin  and  its  consistent  failure  to  have  off- 
spring. 

153 


154  THE  STORY  OF  THE  MAIZE  PLANT 

No  plant  surpasses  maize  in  the  elaborate  dilTerentia- 
tion  of  its  endosperm,  and  many  of  its  characteristics 
give  clear-cut  response  to  genetic  experiments.  It  is 
not  surprising,  then,  that  all  recent  dissertations  on 
"double  fecundation,"  heredity  in  the  endosperm,  or 
the  theoretical  significance  of  the  endosperm  of  angio- 
sperms  have  centered  around  this  one  species. 

Early  development. — The  large  nucleus,  resulting  from 
the  union  of  the  sperm  with  the  two  polar  nuclei,  begins 
immediately  a  series  of  rapid  divisions,  accompanied 
by  an  enlargement  of  the  cavity  formerly  occupied  by 
the  embryo  sac.  Until  fifty  or  more  nuclei  have  been 
formed  in  this  way,  there  is  no  actual  cell  division,  and 
the  developing  endosperm  is  merely  one  large,  multi- 
nucleate cell. 

The  first  walls  appear  cutting  off  uninucleate  cells 
at  the  periphery,  free  nuclear  division  continuing  mean- 
while in  the  interior.  But  the  one  process  overtakes 
the  other  after  a  time,  and  before  the  endosperm  has 
attained  any  considerable  size,  the  free-nuclear  stage  of 
growth  has  ceased.  From  this  time  onward,  growth  pro- 
ceeds both  by  the  enlargement  and  by  the  division  of  cells. 

Nuclear  divisions. — Very  little  is  known  of  the 
cytological  details  of  the  growth  of  the  endosperm  of 
angiosperms  in  general,  and  a  thorough  investigation  of 
this  point  will  go  a  long  way  toward  clearing  up  the 
uncertainty  as  to  its  meaning.  In  the  growing  endosperm 
of  maize,  both  meitotic  and  direct  divisions  of  the  cells 
occur.  The  former  prevail  in  the  free-nuclear  stage,  but 
the  latter,  whatever  they  may  mean,  are  of  common 
occurrence  in  later  development.  When  meitotic  divi- 
sion occurs,  there  is  usually  much  variation  from  the 


THE  ENDOSPERM  155 

expected  triploid  number  of  chromosomes.  From  this, 
and  from  the  frequent  apparently  direct  divisions  of 
nuclei,  it  seems  that  the  exact  quantitative  division  of 
the  chromatin  is  not  so  closely  guarded  here  as  in  ordinary 
meristematic  tissue;  and  this  may  afford  a  partial 
explanation  of  some  phases  of  differentiation  of  the 
endosperm.' 

The  aleurone  layer. — When  the  endosperm  is  almost 
mature,  a  series  of  periclinal  divisions  in  the  outer 
cells  give  rise  to  the  aleurone  tissue,  a  single  layer  of 
small,  uniform,  cubical  cells  forming  a  sort  of  false 
epidermis.  In  the  aleurone  grains  located  in  the  cells 
of  this  layer  is  the  seat  of  the  series  of  pigments  respon- 
sible for  the  red  or  blue  color  of  the  caryopsis  of  some 
varieties. 

These  aleurone  colors  offer  many  problems,  for  whose 
solution  we  must  look  to  the  future.  They  seem  to  be 
due  to  a  single  pigment  existing  in  two  forms  and  acting 
as  an  indicator.  Both  the  red  and  the  blue  forms  are 
soluble  in  either  hot  or  cold  water.  The  red  form  is 
acid,  and  the  blue  one  alkaline. 

Advantage  is  taken  of  this  chemical  behavior  by 
some  of  the  Indian  tribes  of  Central  America,  whose 
staple  crop  is  a  blue  variety  of  corn.  Meal  made  from 
this  variety  gives  to  porridge  or  other  food  a  disagreeable, 
dirty-blue  appearance  not  at  all  appetizing.  But  some 
aboriginal  student  of  home  economics  long  ago  discovered 
that  the  appearance  of  such  food  could  be  materially 
improved  by  the  addition  of  lemon  juice,  which  changed 
the  blue  to  a  delicate  pink;  and  this  custom  is  generally 
practiced  in  some  locahties  today. 

'  Emerson  (54,  56). 


156  THE  STORY  OF  THE  MAIZE  PLANT 

The  red  or  blue  color  of  the  alcuronc  may  be  present 
in  varying  shades  and  in  many  patterns.  In  hybrids 
they  often  take  the  form  of  mosaics  for  the  occurrence  of 
which  no  thoroughly  satisfactory  explanation  has  ever  been 
advanced.  (Plate  II,  Figs.  5, 6.)  Other  mosaics  which  are 
definitely  inherited  also  occur  in  the  aleurone  of  pure  races. 
Good  examples  of  these  are  aflforded  by  the  "sacred  corn" 
of  the  Navajos  (Plate  II,  Figs.  7,  8.),  each  grain  of  which 
has  a  blue  or  red  spot  at  the  tip ;  and  by  a  variety  from 
the  Andes,  which  seems  to  practice  a  type  of  mimicry.' 

Chemical  and  physical  nature. — The  food  stored  in  the 
endosperm  is  chiefly  carbohydrate  and  protein.  Traces 
of  fats  have  been  reported,  but  these  have  probably 
been  due  to  errors  in  the  mechanical  separation  of  the 
endosperm  from  the  embryo  before  analysis.  Deposition 
of  reserve  materials  begins  in  the  outer  cells  of  the 
endosperm  long  before  maturity  of  the  seed,  and  pro- 
ceeds centripetally.  The  physical  differentiations  of  the 
endosperm  are  determined  by  the  nature  and  relative 
amounts  of  food  materials  stored  in  its  different  parts. 

The  reserve  material  of  the  aleurone  is  protein,  but 
both  proteins  and  carbohydrates  are  present  in  the 
remainder  of  the  endosperm.  In  the  dent,  flint,  pop, 
and  soft  varieties,  the  carbohydrate  is  starch;  in  the 
sweet  and  "waxy"  varieties,  it  consists  of  starch  and 
various   products   of    the   hydrolysis   of    starch.^     The 

'  In  the  districts  where  this  variety  is  found,  the  corn  is  infested  with 
an  insect  which  burrows  under  the  pericarp,  and  the  parasite  avoids 
grains  in  which  others  of  its  kind  have  already  burrowed.  By  mimicking 
infested  grains  by  means  of  its  aleurone  colors,  this  variety  apparently 
protectsitself  from  the  insect  with  some  effectiveness.    See  Kempton  (95). 

2  In  the  so-called  "waxy"  corn,  the  carbohydrate  is  in  the  form  of 
an  erythro-dextrin,  a  substance  of  rare  occurrence  as  a  permanent  deposit 
in  plant  tissues  (160). 


THE  ENDOSPERM  157 

protein  in  this  part  of  the  endosperm  of  all  varieties 
seems  to  be  amorphous,  being,  in  all  probability,  merely 
a  constituent  of  the  desiccated  cytoplasm. 

In  the  parts  of  the  endosperm  where  the  protein  or  col- 
loidal carbohydrate  is  sufficiently  plentiful  to  form  a  matrix 
lining  the  spaces  between  the  starch  grains,  the  tissue  is 
hard  and  translucent;  when  the  amount  of  colloid  is 
insufficient  to  fill  all  these  interstices,  the  endosperm  is 
softer  and  more  or  less  opaque.    (Plate  II,  Figs.  9,  10.) 

In  an  individual  grain,  or  in  a  well-defined  variety  in 
which  the  starch  grains  are  uniform  in  size  and  shape, 
the  hardness  of  the  endosperm  is  an  accurate  index  to 
its  protein  content;  but  this  test  fails  in  the  comparison 
of  widely  different  varieties.  Some  very  hard,  ffinty 
varieties  have,  in  their  endosperm,  a  protein  content 
lower  than  that  of  some  relatively  soft  varieties.  In 
the  former,  the  starch  grains  are  large,  angular,  and 
closely  fitted  together,  and  a  small  amount  of  nitrogenous 
material  is  sufficient  to  produce  the  ffinty  character;  in 
the  latter,  the  starch  grains  are  small,  rounded,  and 
loosely  arranged,  and  even  a  large  amount  of  protein  is 
not  capable  of  filling  all  the  spaces  and  producing  hard- 
ness and  translucency. 

The  yellow  pigment  of  the  endosperm  seems  to  be 
intimately  associated  with  this  protein,  and  the  deep- 
yellow  tints  are  almost  always  confined  to  the  corneous 
portions  of  the  endosperm.' 

Little  is  known  of  the  chemical  nature  of  this  yellow 
pigment.     It  is  readily  soluble  in  alcohol,  and  less  so 

'  Some  authorities  report  a  yellow  pigment  in  the  aleurone  of 
varieties  that  do  not  have  one  of  the  other  aleurone  pigments;  but,  if 
these  are  present,  they  are  so  little  different  from  the  colorless  condition 
as  to  be  seen  with  difficulty. 


158  THE  STORY  OF  THE  MAIZE  PLANT 

in  several  other  solvents.  Further  investigation  may 
explain  its  constant  association  with  protein  by  showing 
it  to  be  the  pigment-bearing  portion  of  some  conjugate 
protein. 

The  real  or  supposed  superiority  in  the  feeding  value 
of  yellow  varieties  of  corn,  as  compared  with  white 
varieties,  has  been  explained  by  the  assumption  that  an 
important  vitamine,  similar  to  that  in  the  carrot,  is 
associated  with  this  yellow  pigment;'  but  this  is  hardly 
more  than  a  guess  at  present,  and  positive  evidence  to 
show  that  there  is  any  consistent  difference  in  nutritive 
value  associated  with  difference  in  color  is  still  lacking. 

In  keeping  with  the  centripetal  development  of  food 
materials,  the  dense,  flinty  portion  of  the  endosperm 
is  localized  in  definite  peripheral  regions.  It  may  vary 
in  extent  from  a  very  thin  layer  over  all  portions  of  the 
endosperm  not  in  contact  with  the  embryo,  to  a  mass 
constituting  almost  the  whole  of  the  endosperm;  but 
in  contact  with  the  cotyledon  there  is  always  at  least 
a  small  region  of  floury  endosperm. 

As  a  grain  loses  moisture  at  maturity,  there  is 
invariably  more  or  less  shrinkage;  and  the  floury 
portion  of  the  endosperm  is  often  disrupted  by  the 
appearance  of  an  air-hole.  But  compensation  for 
shrinkage  may  also  be  made  by  the  wrinkling  of  the 
surface  of  the  fruit.  This,  together  with  other  factors, 
makes  the  external  appearance  of  the  fruit  a  good  index 
to  the  physical  and  chemical  nature  of  the  endosperm. 

Endosperm  varieties. — In  the  flint,  pop,  and  floury 
varieties,  the  corneous  portion  of  the  endosperm  is  in  a 
rather  uniform  layer  over  all  the  other  parts  except  the 

'  Palmer  (114). 


THE  ENDOSPERM  159 

base  and  that  portion  in  contact  with  the  scutellum. 
This  layer  is  very  thin  in  the  soft  varieties,  but  in  pop 
varieties  it  may  be  so  thick  that  only  a  small  region  of 
floury  tissue  remains.  The  flints  are  intermediate 
between  soft  and  pop  varieties.  The  uniformity  of  this 
corneous  layer  leaves  no  weak  places  for  wrinkling,  and 
the  external  contour  is  not  affected  by  shrinkage.  Soft 
grains  may  be  distinguished  from  flints  and  pops  by 
the  more  translucent  appearance  of  the  latter.  Flints 
and  pops  may  readily  be  distinguished  by  the  diminutive 
size  of  the  latter,  in  most  cases. 

The  corneous  portion  of  the  endosperm  of  dent  corn 
is  so  disposed  that  it  does  not  cover  the  top  of  the  grain, 
and  this  weak  place  responds  to  shrinkage  by  permitting 
a  pronounced  wrinkle  or  "dent."  (These  various  types 
of  endosperm  are  shown  in  Figs.  146-63.) 

The  peculiar  mixture  of  carbohydrates  present  in  the 
endosperm  of  sweet  corn  is  subject  to  great  decrease  in 
size  on  losing  its  moisture,  and  the  exterior  of  the  grain, 
unsupported  by  anything  like  the  corneous  layer,  takes  on 
a  very  characteristic  wrinkled  appearance  (Figs.  149-51, 
p.  160,  and  167,  169,  171,  p.  167).  When  thoroughly 
dry,  the  interior  mass,  made  up  of  misshapen  starch 
grains  imbedded  in  protein  and  colloidal  carbohydrate, 
assumes  a  translucent,  flinty  appearance  similar  to  that 
of  the  corneous  portion  of  other  varieties. 

Sweet  corn  is  apparently  the  same  as  other  varieties 
except  that  it  has  lost  the  ability  to  produce  fully  devel- 
oped starch  grains.  Hybridization  of  sweet  varieties 
with  soft  starchy  varieties  produces  grains  indicating  that 
sweet  corn  may  be  differentiated  into  soft,  flinty,  and 
dent  varieties  that  cannot  synthesize  starch  efficiently. 


i6o 


THE  STORY  OF  THE  MAIZE  PLANT 


Just  why  they  cannot  do  this  is  not  well  understood, 
but,  from  the  corroded  appearance  of  the  starch  grains 
that  are  formed,  it  seems  probable  that  they  may  be 
built  up  and  then  partly  hydrolyzed,  or  formed  in  the 
presence  of  a  weak  hydrolyzing  agent. 


150 


CS^ 


160 


161 


Figs.  146-63. — Longitudinal  and  transverse  section  of  grains  of  the 
principal  endosperm  varieties:  Figs.  146-48,  dent.  Figs.  149-51,  sweet. 
Figs.  152-54,  fliiit.  Figs.  155-57,  soft.  Figs.  15S-60,  flinty  dent.  Figs. 
161-63,  pop.  In  each  diagram  the  stippled  portion  indicates  the  soft, 
and  the  unshaded  portion  the  corneous,  part  of  the  endosperm. 


THE  ENDOSPERM  i6i 

The  ''popping'^  oj  corn. — One  of  the  peculiar  proper- 
ties of  the  grain  of  corn  is  its  ability  to  "pop"  when 
heated.  This  is,  to  a  degree,  a  characteristic  of  the 
grains  of  all  varieties  of  maize,  as  well  as  of  the  seeds  of 
many  other  grasses;  but  it  is  most  marked  in  the  small, 
flinty  grains  of  the  common  pop  corns.  The  act  of 
popping  consists  essentially  of  a  miniature  explosion, 
resulting  from  the  slow  application  of  heat  to  the  grain, 
in  which  the  endosperm  suddenly  expands,  and  the  grain 
turns  inside  out. 

This  phenomenon  has,  in  the  past,  been  attributed 
to  a  number  of  more  or  less  imaginary  factors.  It  was 
once  supposed  that  the  explosion  was  due  to  the  expan- 
sion of  a  small  volume  of  air  in  the  floury  portion  of  the 
endosperm  in  the  middle  of  the  seed;  but  some  of  the 
best  popping  varieties  are  the  most  poorly  constructed 
for  this,  and  the  marked  changes  in  the  texture  of  the 
endosperm  indicate  that  the  force  causing  the  explosion 
is  distributed  throughout  the  corneous  portion  of  the 
endosperm,  and  not  localized  in  any  one  part.  Until  a 
few  years  ago,  the  favored  theory  seemed  to  be  that 
the  vaporization  of  a  volatile  oil  caused  the  disruption; 
but  the  endosperm  contains  little,  if  any,  oil,  and  seeds 
that  have  been  treated  with  ether  pop  as  well  as  any. 
Pieces  of  endosperm  pop  like  whole  grains. 

A  summary  of  all  that  is  definitely  known  at  present 
of  the  popping  process  (159)  indicates  that  it  is  due  to 
the  expansion  of  the  moisture  content  of  each  individual 
starch  grain,  after  partial  hydrolysis  during  the  heating 
process.  The  confinement  of  this  pressure  for  a  time, 
followed  by  its  sudden  release,  is  an  important  factor, 
and  this  is  the  role  of  the  flinty  matrix  of  protein.     Flinty 


1 62  THE  STORY  OF  THE  MAIZE  PLANT 

varieties  pop  best,  and  floury  ones  to  only  a  slight 
degree.  Pop  corn  combines  flinty  texture  with  small 
size  of  grain  and  afl'ords  the  optimum  conditions  for 
popping.  There  is  little  or  no  indication  that  popping 
is  to  be  attributed  to  any  peculiarity  in  the  minute 
structure  of  the  starch  grain. 

The  popping  process  is  imitated  commercially  in  the 
preparation  of  the  ''puffed"  cereals.  Here  the  grain, 
containing  the  proper  amount  of  moisture,  is  confined 
in  a  metal  drum,  whose  temperature  is  then  raised  to 
the  point  that  experiment  has  shown  to  be  best,  when  a 
sudden  release  of  the  pressure,  brought  about  by  opening 
the  drum,  causes  all  the  partially  hydrolyzed  starch 
grains  to  burst  simultaneously. 


EXPLANATION  OF  PLATES  I  AND  II 

Plate  I  (see  frontispiece) 

Colors  of  the  endosperm  of  maize.  All  of  these  colors  are 
often  incorporated  in  a  single  variety  such  as  some  of  those  grown 
on  Indian  reservations  in  the  western  part  of  the  United  States 
at  the  present  time. 

Plate  II 

Pigmentation  of  the  caryopsis. 

Figs,  i,  2. — Sections  through  peripheral  tissues,  showing 
pericarp  (P),  testa  (T),  aleurone  (.4),  and  starchy  endosperm  (S). 
The  pericarp  may  be  red  or  brown,  ranging  from  the  darkest 
shades  to  others  so  light  that  they  can  scarcely  be  distinguished 
from  white.  The  testa  is  a  crushed  mass  of  colorless  cells.  The 
aleurone  may  be  red,  blue,  or  white,  two  or  all  three  of  these  colors 
sometimes  occurring  in  the  same  grain  in  the  form  of  mosaics. 
In  these  mosaics  each  cell  is  distinctly  one  color  or  the  other,  as 
shown  in  Fig.  2,  which  is  on  the  boundary  Hne  between  blue  and 


PLATE  II 


PIGMENTATION  OF  THE  CARYOPSIS 


THE  ENDOSPERM  163 

white  in  a  mosaic.  The  starchy  endosperm  may  be  either  yellow 
or  white,  depending  on  the  pigmentation  of  the  desiccated  proto- 
plasm fining  the  interstices  between  the  starch  grains. 

Figs.  3,  4. — Variegated  pericarps.  These  must  not  be  con- 
fused with  aleurone  mosaics,  the  seat  of  pigmentation  being 
entirely  different  in  the  two  cases. 

Fig.  5. — An  endosperm  chimera.  The  exact  cause  of  this 
peculiar  distribution  of  pigmentation,  where  the  grain  is  sharply 
divided  into  two  parts,  is  unknown.  It  is  supposed  to  be  due  to 
some  anomalous  behavior  of  the  chromatin  in  the  early  divisions 
of  the  primordial  nuclei  of  the  endosperm.  Grains  of  this  type 
are  to  be  sharply  distinguished  from  those  having  variegated 
pericarp,  as  in  Fig.  4. 

Fig.  6. — A  typical  aleurone  mosaic. 

Figs.  7,  8.— The  peculiar  hereditary  aleurone  pattern  of  the 
Navajo  "sacred  corn." 

Figs.  9,  10.— Cells  from  the  starchy  endosperm  of  soft  and 
flint  corn,  respectively.  (The  cells  have  been  treated  with  iodine, 
which  turns  the  starch  blue  and  accentuates  the  yellow  color  of  the 
nitrogenous  matrix  filling  the  interstices  between  the  starch  grains.) 
The  endosperm  in  Fig.  10  had  only  6  per  cent  protein,  but  this  was 
sufficient  to  fill  the  spaces  between  the  angular  starch  grains  and 
produce  the  flinty  texture.  In  Fig.  9,  the  much  higher  protein 
content  (12  per  cent)  was  insufficient  to  produce  the  flinty  effect. 
Some  flinty  endosperms  having  as  high  as  15  per  cent  to  17  per 
cent  probably  have  the  rounded  starch  grains  with  all  the  inter- 
stices filled  with  the  nitrogenous  material. 


CHAPTER  XXII 

PHYSICAL  CHARACTER  OF  THE  CARYOPSIS 

Many  factors  combine  to  determine  the  general 
physical  nature  of  a  grain  of  corn.  ]\Iuch  of  this  depends 
upon  the  nature  of  the  pericarp  itself,  but  position  on 
the  ear  and  proximity  of  other  grains  also  play  an  impor- 
tant part.  Inasmuch  as  the  last  steps  in  the  process  of 
maturity  have  to  do  with  the  completion  of  the  endosperm, 
the  conditions  under  which  the  grains  mature  are  also  sig- 
nificant, marked  differences  in  appearance  sometimes  being 
produced  by  hastened  maturity  due  to  frost  or  drought. 

Size. — The  size  of  the  fully  matured  grain  is  usually 
limited  by  the  pericarp,  which  is  under  a  high  state  of 
tension  throughout  development.  The  grains  nearest  the 
middle  of  the  ear,  having  the  largest  pericarps  and  being 
in  the  best  position  to  utilize  their  capacity,  are  generally 
the  largest  on  the  ear.  Those  at  the  base  are  often  as 
large,  but  they  are  sometimes  forced  by  pressure  of  the 
husks  to  assume  shapes  in  which  they  cannot  make  the 
best  of  their  limitations;  and  there  is  a  tendency  for 
the  grains  toward  the  tip  of  the  ear  to  decrease  in  size 
as  a  correlation  with  the  indeterminate  nature  of  the 
whole  inflorescence  (Fig.  172). 

Grains  usually  reach  their  maximum  size  when  they 
have  had  opportunity  to  mature  fully  on  an  imperfectly 
filled  ear.  This  condition  not  only  insures  abundant 
nutrition,  but,  by  relieving  pressure  on  all  sides,  gives 
the  grain  an  opportunity  to  make  the  most  of  its  peri- 
carp by  approximating  a  spherical  shape. 
164 


PHYSICAL  CHARACTER  OF  THE  CARYOPSIS     165 

Grains  resulting  from  cross-pollination  have  been 
shown  to  be  larger,  on  the  average,  than  those  produced 
by  self-pollination,  this  being  an  unusual  expression  of 
the  increased  vigor  of  a  hybrid. 

Among  different  varieties,  there  is  a  wide  range  in 
the  size  of  the  grain.  In  some  very  small  pop  varieties, 
the  average  weight  of  the  grain  may  be  as  low  as  .015 
grams,  while  the  average  grain  of  some  of  the  largest 
varieties  grown  around  Cuzco,  Peru,  may  weigh  a 
hundred  times  as  much.  Individual  grains,  representing 
fluctuating  variations,  may  be  selected  to  show  an 
extreme  range  in  size  much  greater  than  this. 

The  smallest  grains  are  to  be  found  in  the  pop 
varieties,  but  certain  soft  varieties  are  known  whose 
seeds  are  much  smaller  than  those  of  some  pop  varieties. 
The  heaviest  grains  probably  occur  in  the  soft  varieties 
from  Cuzco,  and  the  difference  in  volume  between  these 
and  their  diminutive  relatives  in  the  pop  varieties  is 
more  marked  than  their  difference  in  weight,  because  of 
the  greater  density  of  the  corneous  endosperm  of  the 
latter. 

Shape.— The  true  shape  of  a  grain  of  corn,  as  deter- 
mined by  its  pericarp,  is  brought  out  only  when  the 
grain  is  permitted  to  develop  in  isolation,  as  on  a  poorly 
filled  ear,  or  in  a  paniculate  inflorescence.  Under  such 
conditions,  two  distinct  types  of  grain  may  occur:  a 
rounded  one,  tending  to  be  almost  spherical,  and  a 
conical  one  with  a  sharp  apex  at  the  point  of  attachment 
of  the  silk.  In  either  form,  the  embryo,  seeking  to 
assume  its  characteristic  shape,  may  disturb  the  sym- 
metry of  the  whole  grain.  The  form  with  the  rounded 
apex  is  by  far  the  most  common,   the  conical  shape 


1 66  THE  STORY  OF  THE  MAIZE  PLANT 

occurring  most  commonly  in  the  "rice"  or  "rat-tooth" 
varieties  of  pop  corn. 

But  when  a  grain  develops  in  a  well-filled  ear,  it  is 
subject  to  compression  in  two  directions,  and  the  result 
is  a  longer  and  more  slender  grain.  When  an  ear  has 
eight  rows  or  fewer,  a  pressure  is  exerted  on  each  grain 
only  by  other  grains  in  the  same  row;  and,  meeting  with 
no  resistance  in  expanding  tangentially,  the  grain 
becomes  broad  and  fiat  (Figs.  165,  169,  170).  When 
there  are  more  rows  on  the  ear,  the  influence  of  lateral 
pressure  on  the  grain  is  felt,  and  it  assumes  a  trapezoidal, 
or  almost  rectangular,  shape. 

The  long,  slender  grains  of  "shoe-peg"  dent  varieties 
are  produced  on  ears  having  a  large  number  of  rows. 
The  peculiar  long,  irregular  grains  of  Country  Gentleman 
sweet  corn  (Fig.  167),  and  a  few  other  varieties,  are  the 
result  of  unusual  crowding,  due  to  a  structural  peculiarity 
already  discussed.'  Each  pistillate  spikelet  produces  two 
grains  instead  of  one,  and  the  pressure  of  the  developing 
grains  is  so  great  as  to  eliminate  all  semblance  of  rows 
and  all  geometrical  regularity  in  the  shape  of  the  grain. 

At  the  base  of  the  ear  the  pressure  of  the  husks  causes 
a  few  grains  to  be  short,  rounded,  and  asymmetric.  At 
the  tip,  the  absence  of  any  restricting  influence  permits 
the  grains  to  take  on  the  rounded  form  determined  by 
the  pericarp.  The  anomalous  compound,  or  fasciated 
grain,  that  has  occasionally  been  observed^  has  the 
appearance  of  a  grain  bearing  an  embryo  on  each  side. 
Structurally,  it  is  due  to  the  fusion,  during  ontogeny,  of 
two  grains  by  their  dorsal  surfaces.  The  possibility  of 
this  occurrence  is  suggested  by  the  proximity  of  the  two 

'  See  pp.  118,  119.  ^  Wolfe  (170). 


PHYSICAL  CHARACTER  OF  THE  CARYOPSIS     167 

grains  in  a  spikelet  of  Country  Gentleman  sweet  corn,  and 
by  steps  in  development  where  the  primordium  of  the  two 
florets  of  the  spikelets  should  divide.  The  failure  of  this 
division  to  take  place  results  in  the  compound  structure. 


»#l 


164  "^Hr         -f^ 

^^    165       ^ 
166 


^  f 


167 


169  •      ^^0 

mm     I  ^ 

171  ^ 

172 


Figs.  164-72. — Some  types  of  grain:  Fig.  164,  rice,  or  squirrel- 
tooth  pop  corn.  Fig.  165,  the  giant  Cuzco  corn,  from  Peru.  Fig.  166,  a 
well-bred  dent  corn.  Fig.  167,  shoe-peg  grains  of  Country  Gentleman 
sweet  corn.  Fig.  168,  very  small  grains  of  a  pop  variety.  Figs.  169, 171, 
types  of  ordinary  sweet  com.  Fig.  170,  an  eight-rowed  flint  variety. 
Fig.  172,  grains  from  base,  tip,  and  middle  of  an  ear  of  dent  corn. 


1 68  THE  STORY  OF  THE  MAIZE  PLANT 

Color. — The  color  of  the  grain,  as  a  whole,  is  an  optical 
blend  of  all  the  visible  layers  of  color.  The  corneous 
endosperm,  the  aleurone,  and  the  pericarp  have  their 
own  uncorrelated  color  potentialities,  and  the  latter  two 
are  usually  more  or  less  transparent,  allowing  more 
deeply  seated  colors  to  show  through.  As  a  result  of 
these  conditions,  the  pure  blues  and  reds  of  the  aleurone 
may  be  blended  with  the  yellow  of  the  corneous  portion, 
and  any  one,  or  a  combination  of  these,  may  in  turn  be 
overlaid  with  one  of  the  innumerable  shades  and  tints 
of  the  pericarp.' 

'  Correns  (40),  p.  36,  tabulates  the  possible  combinations  of  all  these 
pigments  located  in  the  different  parts  of  the  caryopsis  and  describes 
the  resulting  color  effects. 


CHAPTER  XXIII 
HEREDITY 

The  biological  researches  of  the  first  quarter  of  the 
twentieth  century  have  centered  chiefly  about  the  enigma 
of  heredity;  and  no  general  treatise  on  maize  would  do 
justice  if  it  did  not  discuss,  to  some  degree,  the  special 
aid  that  this  plant  has  given  the  botanist  in  his  attempts 
to  read  this  world-old  riddle. 

The  first  tangible  step  toward  the  modern  genetics 
was  made  by  Gregor  Mendel,  an  Austrian  monk,  more 
than  half  a  century  ago.  How  his  work  remained  in 
obscurity  for  a  generation  is  an  old  story.  But  it  is 
not  so  generally  known  that  the  maize  plant  was  the 
vehicle  by  which  both  Correns  and  De  Vries  later 
developed  the  same  fundamental  principles  of  heredity 
by  contemporary  researches,  rendered  none  the  less 
brilliant  by  the  discovery  of  Mendel's  undisputed  claim 
to  priority.  And  neither  is  it  generally  known  that,  in 
keeping  with  the  eternal  fitness  of  things,  the  credit  for 
first  bringing  this  American  plant  into  the  light  seriously 
in  the  cause  of  genetics  belongs  not  to  Holland  nor  to 
Germany,  but  to  America,  for  McCluer's  (io6)  early 
experiments  with  maize  established  the  facts,  if  not  the 
generalizations,  of  Mendelism,  although  his  published 
results,  like  those  of  Mendel,  were  too  premature  to 
receive  merited  appreciation. 

But  maize  has  not  made  its  sole  contribution  to  our 
knowledge  of  heredity  by  supplying  material  for  pioneers 
in  the  field.  Many  principles  of  more  recent  discovery 
169 


lyo  THE  STORY  OF  THE  MAIZE  PLANT 

have  also  come  to  light  or  been  substantiated  through 
its  behavior.  As  has  been  stated  in  other  connections, 
it  is  an  extremely  variable  plant;  and  its  varieties 
hybridize  readily.  Many  of  the  studies  that  haAT  been 
made  on  the  heredity  of  its  vegetative  aspects  have 
been  of  a  routine  nature,  resulting  in  a  tabulation  of 
characteristics  as  dominant  or  recessive,  or  orthodox  or 
exceptional,  in  behavior;  but  for  the  general  reader 
these  have  a  limited  interest. 

The  phenomenon  known  as  xenia,  made  possible  by 
the  variability  of  the  endosperm,  enables  the  investi- 
gator to  secure  certain  genetic  results  with  maize  in 
fewer  generations  than  with  almost  any  other  plant. 
The  triparental  origin  of  the  endosperm  also  affords 
opportunity  to  test  the  effect  of  a  hereditary  factor  as 
opposed  to  the  double  appHcation  of  its  opposite,  thus 
throwing  light  upon  the  mechanism  of  multiple  factors. 
In  its  immediate  and  striking  response  to  self- 
polHnation,  maize  is  almost  without  an  equal,  and  this 
gives  it  a  prominent  place  in  all  studies  of  the  effect  of 
inbreeding. 

Xenia. — In  the  course  of  ordinary  experiments  in  the 
hybridization  of  plants,  two  generations  must  be  grown 
before  a  perceptible  result  is  obtained,  and  three  are 
necessary  for  the  production  of  a  characteristic  ]\Iendelian 
ratio.  The  first  generation  affords  material  for  the  cross, 
but  the  visible  characteristic  of  the  hybrid  seeds  are 
usually  determined  wholly  by  the  maternal  parent.  In 
the  generation  of  plants  grown  from  these  seeds,  the 
dominance  of  some  characteristics  becomes  apparent. 
Self-pollination  of  these  individuals  of  the  second  genera- 
tion, crossing  them  inter  se,  or  back-crossing  them  with 


HEREDITY  171 

pure  recessives,  gives  seeds  which  will,  in  the  next  genera- 
tion, develop  into  plants  whose  characteristics  satisfy 
certain  theoretical  ratios. 

Advantage  being  taken  of  the  peculiarities  of  the 
endosperm,  the  same  results  may  be  secured  one  genera- 
tion sooner  with  maize.  When  sweet  corn  is  pollenized 
with  a  starchy  variety,  the  embryos  of  the  seeds  are 
unaffected  visibly,  although  certainly  hybrids;  but  the 
influence  of  the  hybridization  is  at  once  apparent  in  the 
endosperms,  which  are  starchy  in  character.  Self- 
pollination  of  a  plant  grown  from  one  of  these  seeds 
produces  sweet  and  starchy  seeds  in  the  monohybrid 
ratio  (3  starchy:  I  sweet). ^ 

To  this  immediate  effect  of  cross-poUination  has  been 
given  the  name  "xenia,"^  the  term  signifying  "a,  gift  of 
hospitality."  Although  loosely  defined  at  first,  the  term 
is  now  applicable,  in  a  strict  sense,  only  to  the  immedi- 
ate effect  that  may  be  produced  in  the  endosperm  of  a 
plant  by  cross-pollination.  It  finds  its  best  expression 
in  maize,  but  it  is  known  to  occur  in  a  few  other  plants.'^ 

Xenia  was  regarded  as  a  curiosity  almost  as  soon  as 
the  white  man  came  into  contact  with  maize,  and  how 
long  the  Indians  had  been  familiar  with  it  before  that 
we  do  not  know.  The  varieties  that  they  cultivated 
exhibited  a  far  wider  array  of  colors  and  endosperm 

'  Grains,  intermediate  in  character,  sometimes  complicate  this 
ratio,  but  the  rarity  of  such  occurrence  justifies  the  use  of  these  well- 
known  varieties  in  explaining  the  principle  of  simple  Mendelian  ratios. 
The  writer  has  given  elsewhere  (160)  a  possible  explanation  of  the 
occurrence  of  these  intermediate  forms. 

^  Focke  (63). 

3  Xenia  has  been  reported  in  hybrids  between  varieties  of  rice, 
between  wheat  and  rye,  and  between  maize  and  teosinte. 


172  THE  STORY  OF  THE  MAIZE  PLANT 

types  than  is  ordinarily  seen  today,  and  the  conditions 
for  the  occurrence  of  xenia  must  have  been  good  at  times. 
We  are  told  on  good  authority  that  the  Indians  did  observe 
it  and  attributed  it  to  the  minghng  underground  of  the 
roots  of  different  varieties.  But,  as  early  as  1724,  we 
find  an  ingenious  New  England  naturalist  (46)  applying 
conclusive  tests  to  this  theory  and  finding  it  inadequate.' 
He  believes  that  the  mixture  that  occurs  must  be  brought 

'  Philosophical  Transactions  (VII,  57-59)  gives  an  abstract  of  this 
communication.  The  following  is  a  part  of  the  abstract  pertaining  to 
maize : 

"The  Indian  com  is  of  several  colours,  as  blue,  white,  red,  and  yellow; 
and  if  they  are  planted  separately,  or  by  themselves,  so  that  no  other 

sort  be  near  them,  they  will  keep  their  own  colour But  if  in  the 

same  field  3'ou  plant  the  blue  com  in  one  row  of  hills,  as  they  are  called, 
and  the  white  or  j'ellow  in  the  next  row,  they  will  mix  and  interchange 
their  colours;  that  is,  some  of  the  ears  of  com  in  the  blue  com  rows,  will 
be  white,  or  yellow;  and  some  again,  in  the  white  or  yellow  rows,  will  be 
of  a  blue  colour  ....  this  mixing  and  interchanging  of  colours  has  been 
observed,  when  the  distance  between  the  rows  of  hills,  has  been  several 
yards;  and  Mr.  D.  has  been  assured,  that  the  blue  com  has  thus  com- 
municated, or  exchanged,  even  at  the  distance  of  4  or  5  rods;  and  particu- 
larly in  one  place,  where  there  was  a  broad  ditch  of  water  between  them. 
Some  of  our  people,  but  especially  the  aborigines,  have  been  of  opinion, 
that  this  commixtion,  and  interchange,  was  owing  to  the  roots,  and  small 
fibers  reaching  to  and  communicating  with  one  another;  but  this  must 
certainly  be  a  mistake,  considering  the  great  distance  of  the  communica- 
tion, especially  at  some  times,  and  cross  a  canal  of  water;  for  the  smallest 
fibers  of  the  roots  of  Indian  corn  cannot  extend  above  4  or  5  feet.  Mr.  D. 
is  therefore  of  opinion  that  the  stamina,  or  principles  of  this  wonderful 
copulation,  or  mixing  of  colours,  are  carried  through  the  air  by  the  wind; 
and  that  the  time  or  season  of  it  is  when  the  corn  is  in  the  earing,  and 
while  the  milk  is  in  the  grain  for  at  that  time,  the  corn  is  in  a  sort  of 
estualion,  and  emits  a  strong  scent.  One  thing  w-hich  confirms  the  air's 
being  the  medium  of  this  communication  of  colours  in  the  corn,  is  an 
observation,  that  a  close,  high  board  fence,  between  two  fields  of  corn  that 
were  of  a  different  colour,  entirely  prevented  any  mixture  or  alteration 
of  colour,  from  that  they  were  planted  near." 


HEREDITY  173 

about  in  some  way  by  something  carried  by  the  wind; 
and  his  theory  is  correct  as  far  as  it  goes,  although  not 
fully  substantiated  and  explained  until  nearly  two 
hundred  years  later. 

Near  the  close  of  the  century  just  past,  the  discovery 
of  "double  fecundation"  in  angiosperms  gave  promise 
of  a  cytological  explanation  of  xenia,  and  new  interest 
was  awakened  in  the  experimental  study  of  the  phenom- 
enon. The  repeated  demonstration  of  the  behavior  of  the 
sperms  of  maize  in  fecundation  has  since  established 
the  fact  that  the  pollen  tube  makes  a  contribution  to 
the  constitution  of  the  endosperm  as  well  as  to  that  of 
the  embryo,  and  that  a  hybrid  embryo  is  necessarily 
accompanied  by  a  hybrid  endosperm.^  This  explains, 
beyond  any  reasonable  doubt,  the  mechanism  of  xenia; 
and  the  transmission  of  hereditary  characters  to  the 
endosperm  of  maize  is  one  of  the  strongest  evidences 
that  we  have  of  the  sexual  nature  of  the  nuclear  fusion 
in  which  the  endosperm  originates. 

The  experimental  work  done  on  maize  in  the  past  two 
decades  indicates  that  xenia  may  be  expected  to  occur: 
(i)  when  the  female  parent  bears  the  recessive,  and  the 
male  the  dominant,  of  a  pair  of  endosperm  factors, 
neither  being  accompanied  by  an  inhibiting  factor  for 
the  dominant;  (2)  when  the  female  parent  bears  a 
dominant  endosperm  factor,  or  combination  of  factors, 
whose  action  is  capable  of  being  inhibited  by  a  factor 
carried  by  the  male;  or  (3)  when  the  male  and  female 
parents,  respectively,  bear  latent  complementary  factors 
whose  interaction  is  necessary  for  the  production  of  a 
definite  effect  in  the  endosperm. 

'  See  (70),  (109),  (154). 


174  THE  STORY  OF  THE  MAIZE  PLANT 

Multiple  factors. — The  multiple  factor  hypothesis 
seeks  to  explain  certain  cases  in  heredity  where  a  single 
visible  characteristic  seems  to  be  due  to  two  or  more 
factors,  any  one  of  which  is  capable  of  producing  the 
same  qualitative  effect.  The  key  to  the  whole  problem 
lies  in  a  question  as  to  whether  two  factors  for  the  same 
characteristic  are  really  any  more  potent  than  a  single 
factor;  and  for  this  question  the  endosperm  of  maize  is 
ready  with  an  answer. 

In  flint  and  soft  corn,  we  have  two  types  of  endosperm 
whose  genetic  behavior  is  of  unusual  interest.  In 
reciprocal  crosses  between  these  two  varieties,  the 
endosperm  produced  always  has  the  physical  character 
of  that  of  the  female  parent.  That  this  unusual  behavior 
is  not  due  to  the  failure  of  the  sperm  to  unite  with  the 
endosperm  nucleus  is  shown  by  selecting  as  the  female 
parent  in  each  cross  a  white  variety,  and  for  the  male 
parent  a  yellow  one.  The  occurrence  of  xenia,  in  each 
case,  with  respect  to  color  indicates  that  the  origin  of 
the  endosperm  is  normal. 

The  cytological  fact  that  the  female  parent  contrib- 
utes two-thirds,  and  the  male  one-third,  of  the  heredi- 
tary material  entering  into  the  organization  of  the 
endosperm  offers  the  explanation  that  two  applications 
of  a  factor  may  form  a  combination  more  potent  than 
one  application  of  the  opposite  factor.  Conventional 
treatment  in  succeeding  generations  gives  results  in 
accord  with  this  hypothesis. 

If  the  difference  between  the  flinty  and  soft  endo- 
sperms is  due  to  a  single  factor  or  a  closely  linked  group 
of  factors,  the  relation  between  the  opposite  allelomorphs 
is  probably  that  of  incomplete  dominance;   and  a  blend 


HEREDITY  175 

would  be  secured  if  an  endosperm  could  be  produced  by 
the  union  of  equal  parts  of  the  two  kinds  of  hereditary 
material.  But  double  fecundation  makes  this  impossible. 
This  raises  also  the  old  question  as  to  whether  a  pair  of 
opposite  allelomorphs  showing  incomplete  dominance 
may  really  be  interpreted  on  the  presence-and-absence 
basis.  It  is  easy  to  see  how  absence  might  dilute  pres- 
ence, producing  an  intermediate  condition,  but  how  a 
further  application  of  absence  could  completely  eliminate 
presence  is  more  difficult  to  comprehend. 

The  histological  and  chemical  properties  of  the  endo- 
sperm indicate,  however,  that  the  flinty  or  soft  character 
is  probably  very  much  more  complex  than  the  experi- 
mental work  done  thus  far  would  indicate.  There  are 
doubtless  many  kinds  of  flints  and  many  kinds  of  softs, 
physical  textures  apparently  alike  being  due  to  widely 
different  sets  of  hereditary  and  environmental  factors, 
and  only  a  better  knowledge  of  the  physical  basis  of  the 
hereditary  phenomena  can  clear  up  this  point. 

The  experimental  data,  together  with  the  theoretical 
explanation,  may  be  seen  from  the  following  summary: 

1.  A  pure  flint  poUenized  with  a  pure  soft  gives 
flinty  grains;  in  the  reciprocal  cross,  soft  grains  are 
produced  (Table  I). 

TABLE  I 

Female  Male  Embryo  Endosperm 

FF        X        SS         =         FS        4-        FFS        (flinty) 
SS         X        FF        =         SF        -f        SSF         (soft) 

2.  Self-pollination  of  either  of  these  hybrids,  or  back- 
crossing  with  either  parent-type,  produces  flinty  and 
soft  grains  in  equal  numbers  (Table  II) . 


176  THE  STORY  OF  THE  MAIZE  PLANT 


TABLE  II 

Female 

Male 

Embryo 

E;ndosperm 

FS 

X 

FS 

=            FF            + 

FFF 

(flinty) 

FS         + 

FFS 

(flinty) 

SF         + 

SSF 

(soft) 

SS         + 

SSS 

(soft) 

FS 

X 

FF 

=         FF        + 

FFF 

(flinty) 

SF         + 

SSF 

(soft) 

FS 

X 

SS 

=         FS         + 

FFS 

(flinty) 

SS         + 

SSS 

(soft) 

3.  A  white  flint,  pollenized  with  yellow  soft,  gives 
yellow  flinty  grains;  a  white  soft,  pollenized  with  yellow 
flint,  gives  yellow  soft  grains  (Table  III). 

TABLE  III 

Female  Male  Embryo  Endosperm 

FFWW  X  SSYY  =   FSWY  +  FFS\V\VY  (yellow  flinty) 
SSWW    X  FFYY  =  SFWY  +  SSFWWY  (yellow  soft) 

4.  Self-pollination  of  either  of  these  latter  hybrids 
gives  flinty  and  soft  grains  in  equal  numbers,  and  yellow 
and  white  in  the  ratio  3:1.  The  whole  population  falls 
into  four  pheno types,  as  follows:  6  yellow  flint,  6  yellow 
soft,  2  white  flint,  2  white  soft  (Table  IV). 

Hybrid  vigor. — The  popular  notion  that  inbreeding  is 
conducive  to  degeneracy,  and  cross-breeding  toward 
increased  vigor,  is  as  old  as  the  practice  of  breeding 
itself;  and  the  mechanism  of  this  behavior  has  been 
sought  in  many  researches.  Maize  is  especially  respon- 
sive to  this  treatment,  and  has  held  a  prominent  place  in 
recent  investigations. 

A  single  generation  of  self-pollination  in  this  plant 
usually  causes  a  marked  decrease  in  vigor;    and  con- 


HEREDITY 


177 


tinued  inbreeding  results  in  still  further  weakened  plants, 
some  of  which  may  be  characterized  by  complete  or 
partial  sterility,  dwarfing,  androgyny,  albinism,  or 
susceptibiHty  to  disease.  But,  after  five  or  six  consecu- 
tive generations  of  this  treatment,  there  comes  a  time 


flinty 


TABLE  IV 

Female                Male 

Embryo 

Endosperm 

WYES  X  WYES 

=  YYFE 

+  YYYEEF 

YYES 

+  YYYEES 

YWEE 

+  YYWEEE 

WYFF 

+  WWYEEE 

YWFS 

+  YYWEES 

WYES 

+  WWYEES  . 

YYSF 

+  YYYSSF    ■ 

YYSS 

+  YYYSSS 

YWSS 

+  YYWSSS 

WYSS 

+  WWYSSS 

YWSE 

+  YYWSSE 

WYSE 

+  WWYSSE  . 

soft 


WWFF  +  WWWEEE\ 
WWES   +  WWWFES  I    ^"^^' 


yellow 


WWSE  +  WWWSSF 

wwss  +  wwwsss 


•white 


>soft 


when  inbreeding  has  no  further  effect,  and  the  races  that 
have  survived  show,  in  their  respective  populations,  a 
striking  uniformity  seldom  seen  under  normal  conditions. 
Some  of  the  abnormal  races  may  survive  to  this  end,  but 
the  lethal  nature  of  the  anomaly  insures  the  extinction  of 
many  of  them. 

Hybridization  of  two  of  these  weakened  races  which 
show  no  anomalies  usually  produces  a  strong,  vigorous 
strain.     The   same   improvement   is    noted   when    two 


1 78  THE  STORY  OF  THE  IVIAIZE  PLANT 

widely  separated  agricultural  varieties  of  maize  are 
crossed.  In  general,  the  more  dilTerent  two  varieties 
are,  or  the  more  widely  separated  their  habitats,  the 
more  marked  is  this  response  to  hybridization. 

These  experiments  indicate  that  in  an  ordinary 
variety  of  maize,  whose  plants  are  accustomed  to  cross- 
poUination  among  themselves,  but  protected  from  hybrid- 
ization with  widely  different  varieties,  there  is  a  degree  of 
heterozygosis  that  can  be  increased  by  crossing  with 
other  varieties,  or  reduced  practically  to  homozygosis  by 
inbreeding. 

The  anomalies  brought  to  light  by  inbreeding  are, 
for  the  most  part,  recessive  characteristics  visible  only 
in  homozygous  individuals.  But  why  should  vigor  be 
such  a  faithful  index  to  the  degree  of  heterozygosis  ? 

One  explanation  of  this  peculiarity  is,  that,  between 
the  two  factors  of  an  allelomorphic  pair,  there  is  an 
indefinable  physiological  interaction  more  conducive  to 
vigor  when  the  dominant  and  recessive  are  paired  than 
when  the  two  dominants  or  the  two  recessives  occur 
together.  The  general  vigor  of  the  plant  would  depend, 
then,  upon  the  number  of  pairs  of  contrasting  factors 
that  took  part  in  its  development.  Inasmuch  as  this 
physiological  interaction  between  allelomorphs  is  purely 
hypothetical  and  has  never  been  demonstrated  experi- 
mentally, this  theory  suggests  a  point  of  attack  but  does 
not  really  solve  the  problem. 

Another  theory  employs  the  machinery  of  modern 
genetics.  Characteristics  conducive  to  vigorous  de- 
velopment are  usually  dominant,  and  the  general  vigor 
of  the  plant  may  depend  upon  the  number  of  dom- 
inant characters  that  it  possesses.     Inbreeding  a  hetero- 


HEREDITY  179 

zygous  individual  produces  less  vigorous  offspring  because 
it  gives  rise  to  separate  strains,  each  of  which  has  only 
a  part  of  the  dominant  characters  of  the  parent-stock. 
Crossing  two  varieties  produces  a  race  more  vigorous 
than  either  parent,  because  it  has  all  the  dominant 
characters  of  both  parents. 

If  this  be  the  principle  concerned,  it  would  seem  that 
races  ought  to  be  secured,  which,  being  homozygous  for 
a  large  number  of  characters,  would  retain  their  vigor 
in  spite  of  inbreeding;  and  that  others,  homozygous  for 
a  large  number  of  recessives,  would  show  no  increase  in 
vigor  on  being  hybridized.  Races  tending  in  these 
directions  are  sometimes  found,  but  the  mathematical 
possibiHty  of  such  occurrences  is  slight,  and  it  is  further 
comphcated  by  linkage. 

Neither  of  the  theories  here  outlined  hopes  to  say 
the  last  word  on  the  question  of  hybrid  vigor  in  plants 
and  animals  in  general,  and  factors  at  present  unknown, 
or  not  seriously  considered,  may  play  important  parts 
in  the  complete  explanation  to  come  in  the  future.  The 
environmental  conditions  under  which  the  evolution  of 
the  maize  plant  has  taken  place  will  especially  be  given 
more  emphasis  in  future  considerations;  for  the  floral 
structure  of  the  plant  and  the  agricultural  practice  of 
ages  have  constituted  a  condition  conducive  to  cross- 
poUination,  and  the  present  genetic  behavior  may  be 
capable  of  explanation  in  terms  of  adaptation. 

Non-Mendelian  views. — ^Although  the  hereditary 
phenomena  here  described  afford  rare  and  striking  sub- 
stantiations of  some  of  the  extreme  applications  of  mod- 
ern Mendelism,  it  is  only  fair  to  state  that  a  number  of 
careful  investigators  question  the  accuracy  of  some  of 


i8o  THE  STORY  OF  THE  MAIZE  PLANT 

these  observations,  or  derive  from  them  very  different 
interpretations.  Up  to  the  present,  these  views  have 
been  iconoclastic  rather  than  constructive,  and  none  have 
offered  any  serious  competition  with  Mendelism  in  the 
eyes  of  the  botanical  public.  But  these  dissenting 
opinions  have  a  decided  value  and  must  not  be  disre- 
garded, even  though  some  of  them  strike  at  the  very 
heart  of  Mendelism. 

Only  the  future  can  tell  whether  or  not  the  modern 
structure  of  genetics  can  stand  the  test.  Investigations 
will  continue,  and  fragments  of  fact  must  come  to  light; 
and,  as  time  goes  on,  it  may  come  to  pass  that  this  plant, 
which  has  done  so  much  to  develop  the  modern  science 
of  genetics,  will  prove  an  agent  to  break  theories  as  well 
as  make  them;  and  it  is  safe  to  predict  that  if  MendeHsm 
itself,  or  its  ornate  embellishments  of  these  later  days, 
shall  ever  crumble  to  dust,  these  same  problematical 
structures  of  the  maize  plant  will  be  present  and  making 
their  contribution  toward  the  revelation  of  truth. 


CHAPTER  XXIV 
BREEDING 

Intelligent  methods  of  breeding  will  probably  give 
greater  returns  from  maize  than  from  any  other  cereal. 
The  variability  of  the  plant,  under  ordinary  agricultural 
conditions,  makes  a  rigid  selection  essential  to  the 
maintenance  of  any  approximate  standard  of  excellence, 
and,  at  the  same  time,  affords  a  standing  promise  of 
improvement.  Only  a  small  amount  of  seed  is  necessary 
for  planting  an  extensive  area,  and  the  seeds  are  aggre- 
gated in  large  units.  These  conditions  reduce  to  a  mini- 
mum the  task  of  seed  selection.  The  monoecious  nature 
of  the  inflorescence  renders  hybridization  easy  of  perform- 
ance, opening  all  the  possibilities  of  securing  new  com- 
binations of  characters  and  the  increased  vigor  of  hybrids. 

Because  of  the  benefits  to  be  derived  from  it,  maize 
breeding  has  been  practiced  for  a  very  long  time.  One 
of  the  important  responsibilities  of  the  medicine  man  of 
the  aboriginal  community  was  to  direct  the  selection  and 
care  of  the  seed  corn.  The  white  man  slowly  learned 
that  he,  too,  must  maintain  the  standard  of  his  crop  by 
breeding.  The  comparative  ease  with  which  the  crop 
could  be  grown  at  first  ehminated  the  spur  of  necessity, 
and  the  Indian's  persistent  mingling  of  the  intangible 
and  mystic  of  his  rehgion  with  the  concrete  practices  of 
his  daily  life  made  him  a  poor  teacher;  and  it  remained 
for  almost  the  closing  years  of  the  past  century  to 
convince  civilized  man  of  the  necessity  of  scientific  corn 
breeding  and  to  teach  him  its  fundamentals. 


1 82  THE  STORY  OF  THE  MAIZE  PLANT 

Methods. — ^From  crude  beginnings  corn  breeding  has 
grown  to  be  an  elaborate  art.  The  indefinite  aim  of 
producing  merely  more  corn  has  given  way  to  an  attempt 
to  reach  definite  ideals  of  perfection  coincident  with 
high  yields.  Many  methods  have  been  employed  in 
the  attainment  of  these  results,  with  an  increasing  use 
in  recent  years  of  the  principles  of  genetics. 

Maize  is  readily  susceptible  to  the  improving  influence 
of  both  hybridization  and  selection.  To  the  latter  of 
these,  we  are  indebted  for  most  of  the  progress  of  the 
past;  but  recent  experimental  work  indicates  that  we 
may  be  now  entering  a  new  phase  of  the  work,  in  which 
hybridization  is  to  assume  a  more  important  role. 

Selection. — The  selective  improvement  of  corn  doubt- 
less had  its  beginning  in  the  almost  unconscious  choice 
at  planting  time  of  the  best  ears  from  the  depleted  store 
left  from  the  previous  year's  crop.  Inefficient  as  was 
this  method,  it  is  far  too  extensively  employed  in  many 
parts  of  America  even  to  the  present  day.  Foresight 
on  the  part  of  the  more  intelligent  farmers  led  long  ago, 
however,  to  an  earlier  and  earlier  selection  of  seed  until 
the  initial  choice  came  to  be  made  in  the  field  at,  or 
before,  harvest  time.  This  practice  not  only  gives  a 
wider  field  for  selection,  but  also  makes  possible  the 
consideration  of  many  fundamentally  important  qualities 
not  exhibited  in  the  ear  alone. 

Some  of  the  most  successful  breeders  of  today  plant 
each  year  in  a  special  plat,  at  considerable  distance 
from  any  other  corn,  the  few  best  ears  available.  From 
this  plat  are  rigidly  selected  the  few  ears  to  be  used  in  a 
similar  planting  the  next  year,  the  bulk  of  this  ehte 
class  being  used  as  seed  for  the  main  crop. 


BREEDING  183 

As  a  check  on  the  marked  variation  in  yield  of  the 
offspring  of  different  ears,  the  "ear- to-row"  test  has  been 
devised.  In  the  breeding  plat,  a  single  row  is  planted 
from  each  ear  entering  into  the  test;  the  yields  of  the 
different  rows  are  found  at  harvest  time,  and  seed  for 
the  next  crop  is  selected  from  the  row  showing  the  best 
yield. 

Hybridization. — ^In  general,  hybridization  offers 
opportunity  for  improvement  in  at  least  three  ways: 
( I )  through  the  combination  in  one  individual  of  the  good 
qualities  of  two  or  more;  (2)  through  the  interaction  of 
latent  factors  to  develop  desirable  new  characteristics; 
and  (3)  through  an  increase  in  vigor.  Attempts  to 
combine  desirable  characteristics  in  maize  have  met  with 
a  degree  of  success,  but  it  is  in  the  production  of  hybrid 
vigor  that  most  has  been  accomplished. 

Technique  of  hybridization. — Few  plants  are  easier  to 
hybridize  than  maize.  The  wide  separation  of  the 
pistillate  and  staminate  inflorescence  makes  emasculation 
unnecessary  or  easily  accomplished.  The  pistillate 
inflorescence  must  be  covered  with  a  paper  bag  or  some 
other  protective  device  before  the  silks  appear.  Pollen 
is  collected  in  paper  bags  tied  over  the  tassels  a  few 
days  before  the  pollination  is  to  be  made.  The  only 
care  needed  is  to  make  sure  that  the  protection  is  ade- 
quate, in  each  case,  and  to  avoid  contamination  with 
stray  pollen  grains  at  the  time  of  actual  poUination. 
The  pollen  grain  has  a  short  period  of  viability,  and 
pollen-carrying  insects  seldom  cause  difficulty. 

When  hybrid  vigor  is  the  only  thing  sought,  a  field 
method  of  hybridization  on  a  larger  scale  is  employed. 
Alternate  rows  in  the  breeding  plat  are  planted  from 


i84  THE  STORY  OF  THE  MAIZE  PLANT 

one  ear  or  a  few  ears  of  one  variety,  and  the  other  rows 
with  a  different  variety.  By  proper  selection  of  the 
two  stocks,  or  by  planting  at  different  times,  the  two 
varieties  are  brought  to  flowering  at  the  same  time. 
Before  any  pollen  has  been  shed,  all  the  plants  of  one 
variety  are  detasseled,  and,  at  harvest  time,  the  seed 
is  selected  from  these  rows.  The  prompt  and  decisive 
results  of  this  procedure  are  giving  the  method  an  exten- 
sive use  in  practical  agriculture. 

Pedigree  breeding. — In  the  application  of  the  prin- 
ciples already  described,  the  breeder  is  unable  to  control 
at  any  time  the  male  parent  of  the  plant  except  by  hand 
pollination,  and  this  renders  impossible  the  maintenance 
of  pedigreed  seed  in  sufficient  quantity  for  practical  use. 
Consequently,  a  true  breeding,  uniformly  good  popula- 
tion cannot  be  expected;  a  high  average  of  quality  and 
yield  is  all  that  can  be  hoped  for,  and  continued  selection 
is  necessary  for  the  maintenance  of  even  this.  But,  by 
first  taking  advantage  of  inbreeding,  even  at  the  sacrifice 
of  vigor,  it  should  be  possible  in  time  to  produce  a 
variety  breeding  true  for  a  combination  of  desirable 
characteristics. 

To  attain  this  end,  a  number  of  pure  lines  are  secured 
by  inbreeding  a  highly  selected  variety  for  several 
generations.  Undesirable  characteristics  are  eliminated 
as  they  occur,  and  only  the  best  strains  are  retained. 
When  homozygosis  has  been  practically  reached  in  a 
number  of  strains  as  indicated  by  the  uniformity  of 
consecutive  generations,  the  lost  vigor  is  regained  by 
blending  the  best  of  these  strains  in  a  hybrid,  and  the 
result  should  be  a  variety  of  limited  variability  and  a 
high  degree  of  excellence. 


BREEDING  185 

The  maintenance  of  such  a  pedigreed  strain  requires 
only  that  it  be  propagated  under  conditions  that  will 
prevent  its  contamination.  At  present,  the  only  way 
of  securing  this  is  by  maintaining  a  breeding  plat  at  a 
distance  of  at  least  a  quarter  of  a  mile  from  other  varie- 
ties, and  preferably  protected  on  the  windward  side  by 
woods,  orchards,  farm  buildings,  or  other  windbreak. 

Co-operative  breeding. — In  a  work  of  this  kind,  there 
is  excellent  opportunity  for  neighborhood  co-operation. 
No  one  ought  to  object  to  growing  exclusively  a  distinctly 
superior  variety  for  his  main  crop,  and  such  sweet  corn 
or  pop  corn  as  might  be  desirable  could  be  planted  at 
such  times  or  in  such  places  as  not  to  be  a  menace. 
Before  such  co-operation  can  be  secured,  however,  the 
usual  barriers  of  selfishness,  ignorance,  and  prejudice 
must  be  broken  down.  The  botanical  nature  of  the 
maize  plant  and  the  fundamentals  of  genetics  must  be 
better  understood  by  the  farmer;  and  there  must  be 
developed  such  pride  in  the  possession  of  thoroughbred 
plants  that  the  farmer  who  persists  in  maintaining  a 
source  of  contamination  in  the  form  of  a  field  of  inferior 
corn  will  suffer  the  same  contempt  as  the  owner  of 
breachy,  scrub  live  stock  used  for  breeding  purposes. 


CHAPTER  XXV 

PRODUCTS  AND  USES 

In  an  economic  way,  maize  is  the  most  versatile  and 
one  of  the  most  dependable  of  the  corn  plants.  The 
size  and  characteristic  physical  and  chemical  properties 
of  the  plant  enable  it  to  fill  a  wide  range  of  human 
needs;  and  it  has  become  so  thoroughly  interwoven  into 
the  life  of  modern  nations  that  no  resource  could  take 
its  place  without  an  economic  revolution.  In  yield 
per  acre,  and  in  the  certainty  with  which  it  produces  a 
good  crop  under  widely  varying  conditions,  it  is  un- 
equaled  by  any  other  cereal.  Some  of  its  uses  are  so 
common  as  to  require  scarcely  more  than  passing 
mention;  but  others,  which  utilize  properties  ordinarily 
little  known,  or  which  are  of  importance  only  in  restricted 
localities,  demand  a  more  thorough  treatment. 

The  grain  is  the  storehouse  of  the  greater  part  of  the 
useful  material  present  in  the  mature  plant.  It  so  far 
surpasses  the  remainder  of  the  plant  in  this  respect 
that  it  is  often  the  only  part  efficiently  harvested,  and 
it  is  usually  made  the  sole  basis  for  estimating  the  value 
of  the  crop.  But,  as  the  necessity  for  conservation 
increases,  the  food  value  of  the  stem  and  leaves  is 
receiving  more  general  recognition;  and  many  unique 
uses  of  all  parts  of  the  plant  have  now  a  permanent 
place  in  the  arts  and  industries. 

Food  for  live  stock. — The  commonest  use  of  corn  is 
for  feeding  live  stock,  and  much  of  the  grain  produced  is 
thus  employed  without  any  preparation  further  than 

1 86 


PRODUCTS  AND  USES  187 

husking.  For  cattle  the  ears  are  usually  broken  or 
chopped  into  small  pieces  because  of  this  ruminant's 
inability  to  shell  the  grain  from  the  cob.  Whole  or 
broken  ears  are  sometimes  fed  to  poultry,  giving  the 
fowls  both  food  and  exercise.  The  shelled  grain  may  be 
fed  to  any  kind  of  stock  that  can  eat  it  in  the  ear  form, 
and  many  kinds  of  stock  can  be  encouraged  to  eat  more 
and  masticate  it  better  when  it  is  shelled. 

Soaking  or  cooking  the  whole  grain  is  widely  practiced, 
and  the  increase  in  palatability  and  digestibility  is 
thought  to  make  the  treatment  profitable  in  most  cases. 
Corn  meal  in  varying  degrees  of  fineness  is  often  used 
alone,  or  as  a  constituent  of  mixed  feeds.  This  may  be 
made  from  the  grain,  the  whole  ear,  or  the  cobs,  the 
latter  having  a  greater  food  value  than  is  generally 
recognized.  Many  by-products  of  manufacturing  pro- 
cesses are  also  made  into  feed  for  stock. 

The  grain  of  corn  has  insufficient  protein  to  make  a 
balanced  ration,  the  deficiency  being  in  the  kind  of 
proteins  present  as  much  as  in  the  total  protein.  As  a 
rule,  about  half  the  total  protein  of  a  grain  of  corn  is 
zein,  and  it  lacks  certain  of  the  amino  acids  necessary 
for  complete  nutrition.  Cottonseed  meal,  tankage,  or 
leguminous  plants  are  usually  employed  to  balance  the 
ration  of  which  corn  is  the  basis. 

The  nutritive  value  of  the  leaves  and  green  stems 
has  long  been  recognized,  and  the  use  of  these  parts,  in 
the  form  of  fodder  or  ensilage,  is  well  known.  Chemical 
analyses  show  that  the  dry  stems,  roots,  and  cobs 
contain  considerable  amounts  of  proteins  and  carbo- 
hydrates; but  there  is  to  be  expected  an  appreciable 
discrepancy  between  actual  content,  as  shown  by  chemi- 


1 88  THE  STORY  OF  THE  MAIZE  PLANT 

cal  analysis,  and  practical  values,  as  shown  by  feeding 
tests.  In  spite  of  popular  opinion  to  the  contrary, 
neither  analysis  nor  feeding  test  show  any  consistent 
difference  in  food  value  between  white  and  yellow  corn. 

The  value  of  corn  as  a  food  can  best  be  realized  in 
terms  of  live  stock  produced  or  supported.  It  produces 
practically  all  the  pork  of  America,  supplemented,  of 
course,  by  the  nitrogenous  foods  necessary  for  a  balanced 
ration;  it  is  fed,  at  least  for  several  weeks,  in  the 
finishing  process  to  miUions  of  cattle  being  fattened 
for  beef;  and  it  supports,  in  part,  countless  numbers 
of  work  animals  on  the  farms  of  America  throughout 
the  year. 

Milling. — The  highly  specialized  structure  of  the 
grain  of  corn  has  led  to  the  development  of  an  interesting 
group  of  milling  and  other  manufacturing  processes. 

In  earlier  days,  corn  meal  was  almost  universally 
made  by  grinding  the  grain  between  stone  burrs,  and 
mills  of  this  kind  are  still  in  use,  but  they  have  largely 
given  way  to  improved  types.  The  texture  of  the 
product  depends  upon  both  the  process  and  the  variety 
of  corn  used.  Flinty  varieties  tend  to  make  a  coarse, 
granular  meal,  while  that  made  from  soft  varieties  is 
usually  finer  and  floury. 

Whole  meal  is  nutritious  and  palatable,  but  the  bran 
is  sometimes  objectionable,  and  the  oil  from  the  embryos 
of  the  grains  seriously  impairs  keeping  qualities.  The 
one  objection  is  avoided  by  bolting,  and  the  other  by 
crushing  the  grains  coarsely  and  removing  the  embryos 
before  grinding. 

The  coarsely  crushed  endosperms,  after  the  removal 
of   the  hulls  and  embryos,   may  also   be  screened   to 


PRODUCTS  AND  USES  189 

standardize  the  size  of  the  particles  and  placed  on  the 
market  as  flake  hominy.  Hominy  grits  is  only  a  more 
finely  divided  product  made  in  the  same  way.  Both  of 
these  products  consist  largely  of  the  flinty  portion  of  the 
grain.  The  soft  portion  is  crushed  so  readily  that  it 
passes  through  the  grading  screens  and  becomes  a  source 
of  meal  or  of  corn  flour. 

Lye  hominy. — One  of  the  oldest  methods  of  preparing 
corn  for  food  was  discovered  by  the  Indians  and  is  still 
extensively  used.  When  the  grain  is  cooked  with  a 
small  amount  of  an  alkali,  such  as  soda,  lime,  or  ashes, 
the  hulls  are  loosened  and  partly  dissolved  until  they  can 
be  washed  off,  and  the  resulting  product  is  lye  hominy. 

Manufactured  products. — Large,  well-equipped  facto- 
ries attain  a  high  degree  of  efficiency  in  separating  the 
grain  of  maize  into  its  constituent  parts  preliminary  to 
the  manufacture  of  its  various  products.  Although 
they  differ  in  details,  all  of  these  follow  the  same  general 
procedure. 

The  grain  is  first  steeped  in  water  for  a  day  or  two 
to  loosen  from  one  another  the  hull,  the  endosperm, 
and  the  embryo.  After  a  coarse  crushing,  for  which 
the  machinery  is  so  adjusted  as  not  to  break  the  embryos, 
the  whole  mass  passes  into  a  separatory  receptacle 
filled  with  water.  Here  the  oily  embryos  float,  the 
hulls  sink,  and  the  endosperm  largely  remains  in  suspen- 
sion. The  starch  and  protein  of  the  latter  are  separated 
by  sedimentation  and  by  differences  in  solubihty.  The 
separated  solids  of  the  grain  are  dried,  and  the  proteins 
in  solution  in  the  water  used  in  the  process  are  recovered 
by  evaporation  to  dryness.  When  subjected  to  pressure, 
the  embryos  yield  crude  corn  oil.     The  oil  cake,  the 


I90  THE  STORY  OF  THE  MAIZE  PLANT 

hulls,  and  the  crude  proteins  enter  into  the  make-up  of 
stock  feeds. 

Corn  oil. — In  utilizing  corn  oil,  the  manufacturer 
takes  his  cue  from  the  refiner  of  cottonseed  oil,  the  two 
offering  much  the  same  possibilities.  The  purified  oil 
has  an  agreeable  taste,  odor,  and  color,  and  is,  in  every 
way,  the  equal  of  olive  oil  for  culinary  purposes.  When 
hydrogenated,  it  is  an  excellent  substitute  for  lard. 
A  vulcanizing  process  converts  a  gum  associated  with 
the  crude  oil  into  a  substitute  for  rubber,  and  large 
quantities  of  the  oil  are  also  used  in  the  manufacture  of 
soaps,  glycerine,  liniments,  dyes,  paints,  varnishes,  and 
oil  cloth. 

Starch. — Commercial  starches  are  prepared  directly 
from  the  amylaceous  product  of  the  initial  separation  of 
the  grain.  Besides  the  ordinary  use  of  starch  in  the 
kitchen  and  in  the  laundry,  there  are  many  others  not 
so  well  known.  It  is  employed  as  an  adhesive  and  as  a 
size  for  cloth  and  paper;  and  it  forms  the  body  of  some 
kinds  of  cosmetics,  soaps,  and  candies. 

On  being  hydrolized,  starch  produces  first  a  series  of 
dextrins  and  then  sugars,  the  ultimate  product  being 
glucose.  Each  of  these  has  numerous  uses.  This 
conversion  of  starch  is  accomplished  by  roasting  or  by 
heating  it  with  water  and  a  minute  quantity  of  hydro- 
chloric acid. 

The  dextrins  are  used  as  a  size  for  cloth  and  paper, 
as  an  adhesive,'  and  as  a  glaze  for  rice  and  for  cofifee. 

Sugar. — Crystalline  corn  sugar  is  used  chiefly  as  a 
substitute  or  adulterant  for  cane  sugar.  Consisting  of 
almost  pure  glucose,  it  is  much  less  sweet  than  cane 

'  The  so-called  "library  paste"  is  largely  dextrin. 


PRODUCTS  AND  USES  191 

sugar,  but  it  has  equal  preserving  properties,  and  is  the 
most  easily  assimilated  of  all  the  sugars.  As  a  food, 
it  is  the  best  of  sugars,  but,  as  a  flavor,  it  is  surpassed 
by  some  others.  It  may  well  be  mixed  with  cane  sugar 
for  purposes  requiring  a  syrup  so  thick  that  cane  sugar 
alone  makes  it  sweeter  than  necessary. 

Syrup. — Commercial  corn  syrup  is  a  product  of  the 
incomplete  hydrolysis  of  corn  starch.  It  is  a  thick 
solution  of  a  mixture  of  glucose  and  dextrins.  It  is 
extensively  used  as  a  food  and  is  also  employed  in 
the  manufacture  of  leather,  chewing  tobacco,  extracts, 
caramel,  soaps,  sponges,  and  hair  tonics. 

Varieties  used  in  manufacture. — The  yield  and  quality 
of  corn  products  is  determined  in  a  large  measure  by 
the  variety  of  grain  used.  For  hominy  and  grits  the 
flinty  varieties  are  best,  but  for  corn  flour  the  soft 
varieties  give  greater  yields.  Meal  and  the  products  of 
the  more  elaborate  manufacturing  processes  may  be 
made  from  any  kind  of  corn,  but  some  give  much  better 
results  than  others.  Because  of  the  cosmopolitan  nature 
of  dent  corn  and  its  ability  to  give  high  yields  per  acre, 
it  is  more  extensively  used  than  any  other  variety 
in  these  processes. 

Both  yellow  and  white  varieties  are  used  for  meal, 
every  locahty  having  a  decided  preference  for  one  or 
the  other;  but  for  hominy  and  the  starch  products, 
white  corn  is  almost  universally  used. 

Because  of  the  marked  variation  in  the  physical  and 
chemical  properties  of  the  grain,  the  breeding  of  more 
palatable  varieties,  and  of  varieties  richer  in  some 
particular  constituent,  offers  a  wide  and  profitable 
field  for  future  work.     The  progress  that  has  already 


192 


THE  STORY  OF  THE  MAIZE  PLANT 


been  made  in  breeding  for  increased  or  decreased  oil  and 
protein  content  suggests  the  possibilities  in  this  direction. 

Sweet  corn. — The  principal  use  of  sweet  corn  is  for 
human  food.  It  is  harvested  as  soon  as  the  grains  have 
attained  their  full  size  but  before  much  carbohydrate 
has  been  deposited  in  them  in  the  form  of  starch.  It  is 
imperative  that  the  green  corn  be  cooked  as  soon  as 
possible  after  removal  from  the  stalk;  otherwise, 
enzymatic  activity  in  the  grain  continues  to  change  the 
sugars  and  dextrins  into  starch,  seriously  impairing  the 
palatabiUty.  While  the  ear  is  still  attached  to  the  plant 
this  change  is  continually  taking  place;  but,  under 
favorable  weather  conditions,  a  new  supply  of  sugar  is 
constantly  coming  into  the  ear  from  the  leaves,  so  that 
there  is  usually  present  enough  of  the  soluble  carbohy- 
drate to  give  the  grain  the  desired  flavor. 

Much  benefit  can  be  derived  also  from  an  observance 
of  the  reversible  behavior  of  the  enzyme  concerned  in 
the  conversion  of  the  carbohydrates  in  the  grain.  It 
seems  that  the  enzyme  that  changes  the  soluble  carbo- 
hydrate into  starch  also  changes  starch  into  the  soluble 
forms,  the  direction  of  the  reaction  being  determined 
by  environmental  conditions,  chiefly  temperature.  Since 
low  temperatures  are  conducive  to  the  formation  of 
the  sugars,  and  high  temperatures  to  the  formation  of 
starch,  it  is  evident  that  the  sweet  corn  that  must  be 
stored  should  be  kept  at  low  temperatures. 

After  removal  of  the  husks  and  silks,  the  ears  are 
usually  roasted  or  boiled;  or  the  grain  may  be  cut  from 
the  cob  and  prepared  in  any  one  of  many  ways.  Corn 
in  the  ''roasting  ear"  stage  is  kept  for  use  out  of  season 
by  canning  or  drying. 


PRODUCTS  AND  USES  193 

Pop  corn. — A  much  wider  use  than  is  generally 
realized  is  given  the  small  varieties  of  corn  that  "pop" 
when  heated.  Popped  corn,  treated  with  butter,  salt, 
sugar,  or  other  flavors,  is  an  important  ware  of  the 
street  vendor.  Meal  made  from  the  popped  grains 
has  many  untried  possibilities  in  the  manufacture  of 
cake  flours  and  breakfast  foods. 

Cane  sugar. — The  juice  of  the  green  stalks  contains 
considerable  amounts  of  cane  sugar,  and  tropical  varie- 
ties seem  to  be  much  sweeter  than  those  grown  in 
temperate  regions.  By  removing  the  ear  at  the  proper 
time,  before  the  grains  are  fully  grown,  it  is  said  that  the 
stem  may  be  made  to  store  so  much  sugar  as  to  rival 
sugar  cane  in  sweetness.  This  sugar  may  be  refined 
and  crystallized,  but  cane,  beets,  and  the  sorghums  offer 
competition  sufficient  to  suppress  the  commercial 
development  of  this  source,  at  least  in  the  immediate 
future. 

Fermented  products. — Corn  furnishes  one  of  the 
cheapest  and  best  materials  for  the  production  of 
fermented  liquors.  The  juice  of  the  stem  has  a  limited 
use  in  this  way,  as  have  the  green  cobs  left  as  a  by-product 
of  the  canning  industry;  but  the  carbohydrates  of  the 
grain  are  of  most  importance. 

The  substance  upon  which  the  organisms  of  fermenta- 
tion are  allowed  to  act  may  be  corn  meal  or  some  of  the 
manufactured  products  of  the  grain,  such  as  corn  syrup, 
starch,  or  glucose;  but  a  mash  made  from  the  sprouted 
grain  is  most  commonly  used.  The  distilled  and 
purified  product  is  grain  alcohol,  or  some  form  of  whiskey, 
depending  upon  the  details  of  manipulation.  The 
residue  left  after  distillation  is  used  for  stock  food. 


194  THE  STORY  OF  THE  MUZE  PLAXT 

By  allowing  fermentation  to  continue  longer  before 
distillation,  the  alcohol  is  changed  into  acetic  acid. 
Much  of  the  ^-inega^  on  the  market  is  a  derivative  of 
this  product,  but  commercial  acetic  add  is  usually  more 
profitably  made  in  other  ways. 

FueJ. — Since  much  corn  is  grown  in  localities  where 
wood  and  coal  are  scarce,  it  finds  at  times  an  important 
use  as  a  fuel.  The  whole  ears,  the  cobs,  or  the  stalks 
may  be  used  in  this  way.  The  cobs  are  especially  good 
for  kindling  fixes  and  for  smoke  fuel  in  the  meat-packing 
industry-.  Attempts  have  been  made  to  produce  gas 
for  fuel  purposes  by  the  destructive  distillation  of  the 
stalks  and  cobs,  and  a  good  quality  of  gas  results;  but 
the  process  has  never  been  worked  out  on  a  dependable 
commercial  basis. 

The  use  of  the  inedible  parts  of  the  plant  for  fuel 
is  a  commendable  act  of  conservation;  but  this  wasteful 
method  of  utUizing  the  energy*  stored  in  the  grain  must 
stand  as  a  severe  indictment  against  the  transportation 
facihties  and  economic  conditions  of  any  countr\'  that 
permits  it  to  occur  while  people  in  other  parts  of  the 
world  are  d\-ing  of  star\-ation. 

The  stem. — The  dr\-  stem  contains  material  of 
nutritive  value,  but  the  low  degree  of  digestibility  and 
the  complicated  processes  involved  in  preparation  will 
long  act  as  a  limitation  to  its  use  as  a  food.  \'arious 
parts  of  the  stem  are,  however,  adapted  to  other  uses. 

A  compressed  layer  of  the  pith  was  formerly  used  as 
packing  under  the  steel  armor  of  battleships,  its  elasticity 
and  absorptive  power  causing  it  to  swell  and  fill  holes 
made  by  solid  shot.  But  the  evolution  of  the  methods 
of  warfare  has  rendered  this  t\-pe  of  construction  obsolete. 


PRODUCTS  AXD  USES  195 

The  pith  is  a  source  of  almost  pure  cellulose.  Its 
principal  use  is  in  the  manufacture  of  nitrocellulose  and 
its  derivatives,  and  the  product  is  said  to  be  superior  to 
that  made  from  cotton.  The  vascular  bimdles  and 
sclerench%T2ia  make  a  good  qualitv'  of  paper,  which, 
however,  has  not  yet  been  able  to  compete  with  the 
products  of  the  wood-pulp  processes. 

Cobs. — ^The  ash  of  the  cobs  is  rich  in  potash.  The 
cobs  of  large-eared  varieties  are  used  for  making  pipe- 
bowls.  All  the  woody  parts  of  the  plant,  especially 
the  cobs,  are  rich  in  pentosans,  from  which  the  pentose 
sugars  and  their  derivatives  are  made.  An  infusion 
of  the  cobs  is  an  excellent  substitute  for  maple  flavor. 

Husks. — In  earlier  daj-s.  the  husks  were  braided  into 
mats  and  rugs,  and  when  torn  into  nne  shreds  they  formed 
a  good  substitute  for  straw  for  filling  piUows  and  mattres- 
ses. The  nber  of  the  husks  may  be  spun  and  woven 
into  a  coarse  cloth;  it  may  also  be  used  for  making  paper. 
In  Mexico  and  parts  of  South  America,  the  large,  outer 
husks  are  used  for  inclosing  tamaks  for  cooking.  The 
thin,  inner  husks  are  used  in  Latin  America  and  other 
parts  of  the  world  for  cigarette  wrappers. 

Medicinal  -zalue. — The  only  part  of  the  maize  plant 
definitely  known  to  have  a  specific  medicinal  value  is 
the  silk  of  the  immature  ear.  An  infusion  of  this  has 
been  used  beneficially  for  certain  urinary  disorders 
and  venereal  diseases,  and,  in  a  few  instances,  as  a 
cardiac  stimulant.  The  active  principle  is  probably 
maizenic  add.  Extracts  or  infusions  of  the  leaves  and 
husks  are  sometimes  used  in  the  home  treatment  of 
difierent  ailments,  but  they  are  of  doubtful  value. 
\\'et  or  dr\-  poultices  made  from  the  meal  or  whole 


196  THE  STORY  OF  THE  MAIZE  PLANT 

grain  are  sometimes  used,  but  their  value  lies  in  their 
great  capacity  for  heat.  Maize  smut  is  sometimes  used 
as  a  substitute  for  the  ergot  of  rye. 

Undeveloped  possibilities. — The  world  has  been  slow  to 
grasp  the  full  potentialities  of  America's  great  gift  to  man- 
kind. Its  heavy  yields,  the  ease  with  which  it  may  be 
grown,  and  its  adaptability  to  conditions  soon  gave  maize 
a  hearty  welcome  into  every  land  in  which  it  can  be  grown 
successfully;  but  it  has  been  used  principally  to  satisfy 
simple  needs.  Much  of  the  total  product  has  been  fed 
to  live  stock  without  manufacture  of  any  kind;  and  our 
recent  attempts  to  minister  to  starving  Europe  have 
disclosed  the  fact  that,  in  many  countries,  maize  is 
considered  unfit  for  human  food. 

The  peculiarities  of  the  endosperm  preclude  the 
possibihty  that  maize  may  ever  take  the  place  of  wheat 
as  a  source  of  flour  for  making  white  bread,  for  it  is 
deficient  in  the  gluten  content  necessary  to  give  it  the 
proper  physical  texture;  but  it  can  be  made  into  whole- 
some, palatable  foods  of  many  kinds,  and  both  theory 
and  practice  indicate  that  in  balance  of  nutritive  proper- 
ties it  is  the  equal  of  wheat.  Now  that  the  need  for 
conservation  is  beginning  to  be  felt,  the  lengthening 
list  of  its  manufactured  products  is  making  for  maize, 
in  the  economic  life  of  the  whole  enhghtened  world,  a 
place  that  no  other  plant  can  fill. 


CHAPTER  XXVI 

MAIZE  IN  ABORIGINAL  AMERICA' 

Someone  has  attributed  to  the  North  American  bison 
the  decadence  of  that  cultured  race  which  has  left  in 
the  mounds  and  other  works  of  the  Mississippi  Valley 
the  marks  of  a  superior  civilization.  As  the  bison  began 
to  appear  on  the  prairies  in  increasing  numbers,  the  ease 
with  which  a  living  could  be  secured  by  following  an 
instinctive  bent  lured  the  farmer  and  the  artisan  from 
their  civilized  pursuits  and  fixed  habitations  into  the 
nomadic  life  of  the  hunter,  which  placed  no  premium 
on  tendencies  toward  civilization. 

In  the  desolate  waste  of  the  frozen  north,  on  the 
other  hand,  or  in  the  arid  regions  of  the  deserts,  the  actual 
demands  of  a  meager  existence  sapped  the  energy  and 
left  little  opportunity  for  anything  but  work. 

Too  much  work  is  as  demorahzing  as  too  much  play ; 
but  somewhere  between  these  two  extremes  there  was 
found  in  some  parts  of  aboriginal  America  a  condition  in 

'  The  material  embodied  in  this  chapter  has  been  collected  from 
many  sources.  In  a  few  instances,  original  papers,  or  reprints  of  the 
older  ones,  have  been  consulted,  but,  inasmuch  as  none  of  the  more 
important  original  sources,  such  as  the  works  of  Acosta,  Sahagun,  or 
De  la  Vega,  have  been  available,  dependence  has  been  placed  in  resumes 
and  extracts  as  given  by  historians  of  modem  times.  In  connection  with 
the  discussion  of  some  of  the  most  striking  topics,  reference  is  made  direct 
to  the  source  of  the  information.  No  attempt  has  been  made  to  deal 
in  any  critical  way  with  mooted  questions  of  history,  archaeology,  or 
ethnology,  except  in  a  few  instances,  where  the  historian's  understanding 
of  the  botanical  nature  of  the  plant  is  clearly  at  fault  and  has  led  to 
misinterpretation . 


1 98  THE  STORY  OF  THE  IMAIZE  PLANT 

which,  although  work  was  necessary  for  a  comfortable 
living,  yet  intelligent  action  was  rewarded  with  much 
leisure.  This  was  the  promise  of  agriculture,  and  the 
key  to  this  industry  was  Indian  corn.  Only  a  few  favored 
spots  in  all  America  supported  races  that  approached  a 
condition  of  civilization;  and  these  were  the  localities 
where  fixed  habitations  and  relief  from  constant  physical 
effort  were  made  possible  through  the  efficient  cultivation 
of  maize. 

Maize  areas. — By  the  close  of  the  fifteenth  century 
the  cultivation  of  maize  had  become  as  widespread  in 
both  North  and  South  America  as  conditions  of  soil  and 
climate  would  permit.  Its  range  extended  from  the 
Gulf  of  the  St.  Lawrence  and  the  Dakotas  far  down  into 
Chile  and  Argentina,  but  it  was  most  successfully  grown 
between  the  fortieth  parallels  (Fig.  8) . 

Peru  and  Mexico  were  the  seats  of  the  most  advanced 
agriculture  and  general  civilization  reached  anywhere  in 
ancient  America.  Fixed  habitations,  well-built  cities, 
and  good  government  encouraged  the  tiller  of  the  soil 
to  conserve  fertility  and  to  improve  his  land  from  year 
to  year.  Agriculture  was  a  highly  respectable  occupa- 
tion, all  grades  of  society  taking  part  in  it  except  the 
nobility  and  the  military  class  in  time  of  war.  The 
women  sometimes  worked  in  the  fields,  but  the  heavy 
labor  was  mostly  done  by  men. 

In  the  moist,  hot  climate  of  the  Amazon  Valley, 
manioc  largely  took  the  place  of  maize  as  a  staple  food 
crop.  But  the  highlands  of  eastern  Brazil  and  the 
northern  coast  of  South  America  supported  a  hetero- 
geneous, nomadic  population  which  depended  upon  maize 
for  a  part  of  its  subsistence. 


MAIZE  IN  ABORIGINAL  AMERICA  199 

The  maize  area  most  influential  in  the  colonization 
and  development  of  America  comprised  all  that  section 
of  the  United  States  east  of  the  arid  plains  region,  and 
extended  in  some  places  as  far  as  50  miles  into  Canada. 
Hunting  and  agriculture  were  the  dependable  occupa- 
tions. Maize  was  the  chief  staple  food  plant.  The 
population  lived  for  the  most  part  in  wigwams  or  other 
light  huts  of  a  temporary  nature.  The  work  of  clearing 
the  ground  and  cultivating  the  crops  was  left  largely  to 
the  women.  It  was  mostly  a  roving  sort  of  life,  and 
little  progress  was  made  in  agriculture. 

Here  and  there,  however,  strong  tribes  became  well 
established,  built  good  houses,  and  cultivated  the  same 
fields  year  after  year.  Early  explorers  tell  of  vast  areas 
planted  in  maize  and  estimate  in  millions  of  bushels  the 
amounts  of  grain  stored  in  the  largest  villages.  These 
communities  were  the  centers  around  which  a  degree  of 
civilization  the  equal  of  that  of  Mexico  or  Peru  would 
doubtless  have  developed  had  the  white  man  delayed  his 
coming  a  few  centuries  longer. 

Origin  of  maize  culture. — -Indian  myths  of  the  crea- 
tion, the  deluge,  and  the  origin  of  civilization  abound  in 
tributes  to  the  part  played  by  maize,  and  this  plant  is 
the  subject  of  every  legend  that  attempts  to  explain  the 
beginnings  of  agriculture. 

The  early  Aztec  felt  himself  the  superman  and 
boasted  of  his  being  a  "corn-eater,"  while  his  barbarian 
neighbors,  who  took  a  precarious  chance  at  a  living  by 
hunting,  were  mere  "suckers  of  blood.'" 

One  of  the  most  elaborate  myths  found  anywhere  in 
the  literature  of  the  Indians  comes  from  the  Mayas  of 

'  Bancroft  (5),  p.  344- 


200  THE  STORY  OF  THE  MAIZE  PLANT 

Yucatan.  This  recounts  how  certain  gods,  or  godlike 
men,  recently  arrived  in  the  land  and  much  displeased 
with  living  conditions,  planned  to  reclaim  the  natives 
from  barbarism.  After  mature  deliberation,  four  bar- 
barian chiefs  were  sent  to  a  distant  land  to  get  new 
ideas.  They  returned  bringing  with  them  the  "ears  of 
yellow  maize  and  of  white,"  which  rounded  out  their 
scheme  of  existence  and  became  their  chief  reliance  for 
food.' 

Another  tradition  of  the  Mayas  makes  corn  the  very 
breath  of  life  that  was  breathed  into  man.  Made  of 
earth,  he  was  without  life;  but,  by  means  of  maize,  he 
was  converted  into  flesh  and  blood. ^ 

In  an  account  of  the  Canaris,  two  brothers  escape  the 
deluge  by  climbing  a  mountain  in  Ecuador.  When  the 
waters  subside,  they  descend  in  search  of  food.  Two 
parrots  repeatedly  visit  the  famishing  men,  giving  them 
food  and  drink  made  of  maize.  One  of  the  birds  is  cap- 
tured, whereupon  she  miraculously  changes  into  a  beau- 
tiful woman.  She  gives  the  men  the  seed  of  maize  and 
teaches  them  its  culture  and  uses,  and  ultimately  becomes 
the  ancestress  of  the  Canari  race.^ 

The  Navajos  say  that  they  first  knew  of  corn  when  a 
turkey  hen  came  flying  from  the  direction  of  the  morning 
star  and  shook  from  her  feathers  an  ear  of  blue  corn.'' 

In  a  tradition  of  one  tribe  of  the  United  States,  the 
Great  Spirit  comes  to  earth  in  the  form  of  a  woman  and 
falls  asleep.  On  waking,  she  arises  and  walks  through 
the  land,  while  useful  plants  spring  up  around  her.  At 
the  right  and  left  grow  pumpkins  and  beans,  and  from 

■  Bancroft  (5),  pp.  715-17-         ^Ibid.,  pp.  361-62. 
•  Payne  (116),  p.  357.  •»  Sturtcvant  (138). 


MAIZE  IN  ABORIGINAL  AMERICA  201 

her  footprints  comes  maize.  The  spot  where  she  slept 
gives  rise  to  tobacco. 

The  fact  that  these  traditions  account  for  the  intro- 
duction of  maize  in  various  miraculous  ways  and  in 
different  places  has  led  some  historians  to  believe  that 
the  plant  had  more  than  one  place  of  origin;  and  the 
many  varieties  of  the  plant  are  cited  in  support  of  this 
theory.  But,  since  we  must  reject  so  much  of  the 
mythical  as  to  the  manner  of  its  origin,  may  we  not 
reasonably  question  also  the  time,  and  to  a  less  degree 
the  place  ?  A  botanical  study  of  the  many  varieties  shows 
only  superficial  differences  between  them  and  points 
to  a  wild  ancestor  that  was  much  like  the  modern  plant. 

It  is  probable  that  the  podded  character  had  been 
lost  and  the  eight-rowed  ear  had  made  its  appearance 
before  the  plant's  usefulness  and  domesticability  first 
appealed  to  the  savage.  The  effect  of  cultivation  has 
been  chiefly  to  reduce  the  number,  and  increase  the 
size,  of  the  inflorescences,  and  to  concentrate  the  fruit 
into  one  or  a  very  few  units. 

Similarities  in  nomenclature  and  agricultural  practice, 
together  with  what  is  known  of  the  early  migrations  of 
Indian  tribes,  point  unmistakably  to  Mexico  or  Central 
America  as  the  locality  in  which  the  domestication  of 
maize  began.  From  here  the  plant  made  its  way  both 
northward  and  southward,  passing  on  and  on,  from  tribe 
to  tribe,  as  its  importance  came  to  be  appreciated.  The 
number  of  stable  varieties  that  were  grown  in  1492,  the 
absence  of  any  wild  ancestral  form,  and  the  well- 
established  customs  and  traditions  surrounding  the 
maize  plant,  point  to  a  long  period  of  domestication 
before  the  coming  of  the  white  man. 


202  THE  STORY  OF  THE  MAIZE  PLANT 

Evolittion  of  maize  culture. — Even  when  the  barbarian 
had  first  come  into  contact  with  maize,  and  a  dim  real- 
ization of  its  value  had  awakened  within  him,  anything 
like  an  efiicient  system  of  agriculture  was  still  far  in  the 
distance;  and  the  evolution  of  man's  methods  in  deal- 
ing with  the  plant  is  scarcely  less  significant  than  its 
botanical  evolution.  Much  aimless  or  superstitious 
experimental  work  must  have  been  done,  and  many 
exasperating  failures  must  have  been  experienced,  before 
the  working  principles  of  the  art  were  mastered;  and 
in  the  traditions  of  the  tribes  we  find  more  or  less  definite 
reference  to  these  difficulties.  No  act  of  god  or  man  in 
giving  the  seed  of  maize  to  a  tribe  was  complete  unless  the 
gift  was  accompanied  by  directions  as  to  its  culture  and 
uses;  and,  even  then,  successful  manipulation  required 
long  experience. 

A  tradition  of  the  Toltecs,  who  occupied  Mexico  long 
before  the  day  of  the  Aztecs,  will  illustrate.  Maize 
culture  was  at  first  very  difficult,  because  of  unfavorable 
weather.  Famine  and  plundering  raids  by  savage  tribes 
destroyed  a  large  part  of  the  population,  and  agriculture 
was  abandoned  in  a  reversion  to  hunting.  Long  years 
after  this,  a  chief  planted  a  few  grains  of  maize  that  he 
had  saved,  and  the  result  was  so  encouraging  that  a  new 
impetus  was  given  to  agriculture.  Later,  in  the  days  of 
the  first  of  the  Montezumas,  frosts  caused  the  crops  to 
fail  for  two  successive  years,  and  a  drought  in  the  third. 
Famine  followed,  and  the  discouraged  farmers  planted 
no  maize  the  next  year.  But  the  season  was  favorable, 
and  a  bountiful  crop  grew  spontaneously.  This  miracle 
revived  an  interest  in  agriculture;  but  failure  had  taught 
its  lesson,  and  scientific  methods  of  seed  selection  and 


MAIZE  IN  ABORIGINAL  AMERICA  203 

storage,  planting,  and  cultivation  began  to  be  practiced. 
It  was  probably  some  such  disaster  as  this  that  suggested 
the  first  system  of  irrigation.' 

Among  the  shiftless,  wandering  tribes  of  both  con- 
tinents might  be  found  every  imaginable  step  in  the 
evolution  of  agriculture,  and  many  of  these  are  suggested 
in  the  traditions  of  the  more  progressive  tribes. 

Man's  first  cornfield  was  a  natural  opening  in  the 
forest,  or  a  spot  where  the  trees  had  been  accidentally 
killed  by  fire.  The  next  step  was  to  clear  the  ground 
roughly  by  girdhng  the  trees  and  burning  the  underbrush. 
Ground  cleared  in  this  way  produced  from  eighty  to 
four  hundred  fold  the  first  year;  but  the  yield  rapidly 
decreased  in  succeeding  years  until  too  low  to  be  profit- 
able, when  the  old  tract  was  abandoned  and  a  new  one 
cleared.  When  this  practice  had  exhausted  all  the  land 
convenientaly  located,  and  it  became  apparent  that  the 
friendship  of  some  god  had  begun  to  wane,  as  evinced 
by  the  failing  crops,  the  tribe  moved  on  to  a  new  locality. 
Civilization  was  impossible  until  the  abihty  to  select  good 
soil  and  to  retain  its  fertility  made  permanent  settlements 
possible.  In  the  areas  of  most  intensive  cultivation 
in  later  days,  many  kinds  of  fertilizers,  such  as  manures, 
fish,  ashes,  or  guano,  were  used  very  successfully. 

It  was  a  remarkable  stroke  of  Providence,  which, 
withholding  from  the  native  American  any  domesticable 
animal  that  could  be  used  in  tilling  the  soil,  gave  him  in 
compensation  the  one  important  cereal  adapted  to  cul- 
tivation by  hand.  With  one  or  two  exceptions  of  a 
crude  nature,  no  sort  of  plow  or  harrow  is  known  to  have 
been  used  anywhere  in  ancient  America. 

■Payne  (116),  pp.  358-59. 


204  THE  STORY  OF  THE  MAIZE  PLANT 

The  most  primitive  method  of  manipulation  consisted 
of  merely  planting  the  corn  in  holes  made  with  a  sharp 
stick,  and  leaving  it  without  further  attention  till  harvest 
time.  Gradually,  the  farmer  learned  the  importance  of 
killing  weeds  and  loosening  the  soil  and  heaping  it  up 
around  the  plants  for  support. 

The  practice  of  planting  corn  in  hills  seems  to  have 
been  universal,  the  number  of  plants  in  a  hill  often  being 
as  high  as  ten  or  twelve.  The  distance  between  the  rows 
and  between  the  hills  in  a  row  was  dictated  by  moisture 
and  fertility.  To  secure  a  good  stand,  the  seeds  were 
often  germinated  before  planting,  and  care  was  usually 
taken  to  see  that  the  seeds  in  a  hill  were  spaced  at  some 
distance  from  one  another.  The  compact  hills  seen  in 
a  modern  cornfield,  where  the  three  or  four  stalks  are 
often  so  close  together  that  they  are  in  actual  contact 
with  one  another,  was  unknown  to  the  Indian.  He 
planted  the  corn  in  hills  so  that  he  could  heap  the  soil 
around  the  plants  in  groups  rather  than  singly,  and  he 
made  the  hill  worth  while  by  putting  in  it  a  large  number 
of  plants ;  but  these  were  often  so  spaced  that  the  plants 
covered  an  area  a  foot  or  more  in  diameter. 

After  the  corn  had  reached  the  height  of  a  few  inches, 
beans  were  sometimes  planted  in  the  hills  and  allowed 
to  twine  around  the  corn  plants  as  they  grew.  The  corn- 
field was  often  made  to  support  also  an  undergrowth  of 
pumpkin  vines.' 

The  sunplest  implements  used  in  the  cultivation  of 
the  crop  were  sharp  sticks,  shells,  bones,  or  other  objects 

I  An  Indian  story  often  told  for  the  amusement  of  the  children 
pictures  the  bean  and  the  pumpkin  as  two  suitors  of  the  maize  lady. 
The  one,  being  favorably  received,  holds  her  in  his  embrace,  while  the 
rejected  lover  runs  away  over  the  ground. 


Fig.  173. — A  hill  of  corn.  The  growing  of  corn  in  hills  has  been 
practiced  by  the  Indians  for  ages,  and  this  ecological  condition  must  be 
constantly  kept  in  mind  in  theoretical  considerations. 


2o6  THE  STORY  OF  THE  MAIZE  PLANT 

that  could  be  used  as  they  were  found.  Modifications 
of  these  implements  to  improve  their  efificiency  led  to 
the  use  of  many  ingenious  devices.  Sharpened  sticks  were 
hardened  by  being  charred  in  the  fire.  Hoes  of  various 
types  were  made  by  fastening  shells,  bones,  or  pieces  of 
wood  or  stone  to  handles,  or  by  working  a  part  of  the 
trunk  of  a  small  tree  into  a  flat  blade,  while  a  branch 
attached  to  it  was  made  to  serve  as  a  handle.  Spades 
were  made  in  a  similar  way,  one  form  consisting  of  a 
straight  stick  sharpened  and  charred  at  the  lower  end, 
and  bearing  the  short  stump  of  a  branch  as  a  place 
for  the  foot.  In  rare  instances,  the  implements  used 
in  working  the  soil  were  made  of  copper  or  other 
metal. 

Varieties  of  maize.— AW  the  fundamental  varieties  of 
maize  in  existence  today,  as  determined  by  the  nature 
of  the  endosperm,  seem  to  have  been  known  to  the  various 
Indian  tribes.  The  choice  among  available  varieties  of 
the  one  best  suited  to  a  particular  set  of  conditions 
seems  to  have  been  made  about  as  intelligently  then  as 
now.  The  Indian's  taste  for  the  gaudy  kept  in  common 
use  a  wider  range  of  colors  than  is  known  to  the 
average  American  today.  Sometimes  the  full  array  of 
white,  reds,  yellows,  and  purples  were  maintained  in 
a  single  variety,  and  again  pure  strains  were  often 
propagated  for  generations,  some  of  these,  such  as 
the  "sacred  corn"  of  the  Navajos,  showing  striking  color 
patterns. 

Agricultural  engineering. — Some  of  the  most  stupen- 
dous feats  of  engineering  accomplished  in  prehistoric 
America,  or  anywhere  in  the  ancient  or  medieval  world, 
were  connected  with  the  growing  of  maize. 


MAIZE  IN  ABORIGINAL  AMERICA  207 

The  simplest  engineering  projects  were  the  "garden 
beds"  of  the  Mississippi  Valley/  In  the  tough  sod  of 
the  prairies  of  southern  Michigan  and  Wisconsin  and 
northern  Indiana  are  still  to  be  seen  ridges  and  mounds 
used  for  growing  corn  in  ancient  times.  These  beds 
consist  of  a  series  of  parallel  or  regularly  curved  ridges, 
the  construction  of  which  must  have  called  for  a  high 
degree  of  skill.  They  probably  had  their  origin  in  the 
custom  of  planting  the  corn  each  spring  in  the  ridge  left 
by  the  cultivation  of  a  row  the  previous  year.  The 
heaping  up  of  the  soil  year  after  year  finally  built  up  a 
ridge  that  has  endured  in  some  places  to  the  present. 
Sometimes  the  ridges  were  wide  enough  for  but  a  single 
row,  and  again  they  were  spaced  at  greater  intervals  and 
made  wide  enough  for  two  or  more  rows. 

Although  the  best-preserved  examples  of  these  struc- 
tures are  to  be  found  about  the  western  border  of  the 
Great  Lakes,  traces  of  similar  works  occur  throughout 
the  Mississippi  Valley  and  the  West  Indies. 

The  construction  of  these  beds  was  probably  the 
work  of  that  problematical  race  known  as  the  Mound 
Builders  rather  than  of  the  Indian  of  later  days.  Their 
vast  extent — -continuous  areas  of  twenty  to  a  hundred 
acres  being  known — indicates  a  stable  government  and 
a  high  degree  of  civilization.  The  dense  population 
indicated  by  these  and  contemporary  works  of  other 
kinds  was  doubtless  supported  largely  by  the  cultivation 
of  maize,  inasmuch  as  many  of  the  mounds  that  have 
been  opened  contain  supplies  of  this  grain  and  fragments 
of  the  plant. 

'  Critics  disagree  as  to  the  significance  of  these  works,  some  even 
doubting  their  connection  with  prehistoric  agriculture.  The  resume 
here  given  is  based  chiefly  upon  Schoolcraft  (130),  pp.  54-60. 


2o8  THE  STORY  OF  THE  IMAIZE  PLANT 

The  early  culture  of  the  Aztecs  was  developed  on 
islands  in  the  lakes  of  central  Mexico,  where  the  popula- 
tion has  sought  refuge  from  their  enemies.  As  their 
island  homes  became  crowded,  rafts  were  built  and 
covered  with  mud  and  tangled  vegetation  dipped  up  from 
the  bottom  of  the  lake.  This  mass  was  in  time  bound 
together  with  the  roots  of  growing  plants  and  became  a 
floating  garden.  A  tiny  hut  and  a  patch  of  corn  made 
it  complete,  and  the  owner  had  a  safe,  portable  farm 
that  needed  no  fertilizers  and  no  irrigation. 

On  the  steep  slopes  of  the  Andes,  the  surface  available 
for  cultivation  was  often  materially  increased  by  terra- 
cing. Contour  lines  were  marked  with  banks  of  earth  or 
walls  of  stone,  and  soil  was  brought  up  from  below  to 
fill  in  the  terraces.  Irrigation  was  often  employed  to 
remove  the  one  defect  of  this  system  of  agriculture,  and 
these  terraces  were  said  to  have  produced  the  heaviest 
yields  of  maize  known  anywhere  in  America. 

In  the  desert  valleys  of  Peru  and  Chile,  the  loose 
sand  is  often  underlaid  by  a  moist,  fertile  subsoil,  which 
was  sometimes  made  available  by  the  removal  of  the  sand. 
Some  of  the  pits  thus  formed  were  as  much  as  20  feet 
deep  and  covered  an  acre  or  more.  In  these  could  be 
grown  maize  and  other  plants  without  irrigation. 

But  surpassing  all  other  feats  of  engineering  under- 
taken by  the  Indian,  and  making  no  mean  showing  beside 
similar  works  of  the  present  day,  were  the  gigantic 
irrigation  projects  of  ancient  Peru.  The  valleys  and 
mountain  sides  of  many  parts  of  the  Andes  have  only  a 
scanty  rainfall  irregularly  distributed;  and,  to  secure  a 
dependable  supply  of  moisture  for  his  cornfield,  the 
Inca  and  his  neighbors   built   aqueducts   hundreds   of 


MAIZE  IN  ABORIGINAL  AMERICA  209 

miles  in  length,  bridging  streams,  and  tunneling  moun- 
tains, and  doing  the  work  so  well  that  it  stands  in 
serviceable  form  in  many  places  today.  Irrigation  was 
also  extensively  practiced  in  Mexico. 

All  these  massive  works  of  the  past  stand  today  as 
mute  witness  of  the  part  that  the  maize  plant  played  in 
the  life  of  the  native  American.  It  was  not  only  impor- 
tant enough  to  call  forth  this  stupendous  effort,  but  it 
also  provided  food  in  sufificient  abundance  to  release  enor- 
mous numbers  of  laborers  for  public  works  of  this  kind. 

Harvesting  and  storage. — In  most  instances,  the  ears 
of  corn  were  left  on  the  stalk  in  the  field  until  dry. 
Since  the  ears  of  many  varieties  stood  erect  at  maturity, 
it  was  the  custom  in  some  places,  as  soon  as  the  corn 
was  mature,  to  break  the  stalks  over  just  below  the  ears 
so  that  the  latter  would  hang  downward  and  be  sheltered 
by  the  husks  while  drying. 

The  ripe  ears  were  sometimes  spread  out  on  platforms 
to  become  thoroughly  dry.  At  other  times,  the  ears 
were  broken  off  and  the  husks  pulled  back  and  braided 
together,  and  long  chains  of  the  ears  thus  united  were 
hung  over  poles  to  dry.  The  grain  was  sometimes 
shelled  before  storage,  but  was  often  stored  in  the  ear. 

A  favorite  storage  place  among  all  tribes  was  in  pits 
in  the  ground.  In  Eastern  North  America,  these  were 
lined  with  bark,  leaves,  or  dried  grass.  In  Mexico  and 
Peru,  the  grain  was  often  stored  in  these  pits  in  vessels 
of  pottery.  In  many  places,  there  was  used  a  type  of 
crib  made  of  poles.  Each  family  had  one  or  more  pits 
or  cribs  containing  enough  grain  for  its  own  use,  and 
there  were  often  great  stores  reserved  for  the  common 
use  of  the  whole  community  in  cases  of  emergency. 


2IO  THE  STORY  OF  THE  MAIZE  PLANT 

Uses. — The  Indian's  simple  requirements  discovered 
only  the  most  obvious  and  most  fundamental  uses  of 
the  maize  plant.  The  part  most  used  was,  of  course, 
the  mature  fruit,  but  other  parts  had  a  recognized  value. 

In  preparing  the  dry  grain  for  use,  the  first  step  was 
to  remove  the  tough,  leathery  hull  of  each  grain.  Some- 
times the  dry  grain  was  crushed  in  a  stone  or  wooden 
mortar  and  the  hulls  sifted  out.  In  some  places,  it  was 
customary  to  boil  the  grain  and  remove  the  pericarps  one 
at  a  time  by  hand.  This  method  was  especially  apph- 
cable  to  the  large  grains  of  the  varieties  grown  about 
Cuzco,  Peru.  But  the  most  popular  method  was  to  boil 
the  corn  in  water  to  which  ashes  or  lime  had  been  added. 
This  method,  which  loosens  and  partly  dissolves  the 
hulls  without  impairing  the  food  value  of  the  grain,  is 
still  extensively  used  by  civilized  man  in  making  lye 
hominy. 

The  hulled  grain  was  either  boiled  and  eaten  as 
hominy,  crushed  and  made  into  porridge,  or  made  the 
basis  of  a  bread  or  similar  food.  Typical  of  the  last 
were  the  tortillas  of  the  Mexican  Indians,  a  kind  of  bread 
known  under  various  names  to  all  maize-growing  tribes. 
The  boiled  corn  was  crushed  and  made  into  a  thin 
batter,  which  was  baked  in  thin  cakes  on  a  flat  rock  or 
in  an  earthen  pan.  These  cakes  were  the  staple  food 
made  from  corn.  Tamales  were  pies  made  of  various 
kinds  of  meat  wrapped  in  masses  of  dough,  the  whole 
being  inclosed  in  a  corn  husk  or  banana  leaf  and  baked 
or  boiled. 

Pop  corn  was  known  in  many  localities,  and  parched 
corn  was  widely  known  and  used  in  many  ways.  The 
latter,  when  ground,  was  often  used  on  long  journeys 


MAIZE  IN  ABORIGINAL  AMERICA  21 1 

where  the  maximum  of  food  was  to  be  carried  in  a  small 
packet. 

Though  the  Indian  was  fully  aware  of  the  substantial 
way  in  which  maize  supplied  some  of  his  fundamental 
needs,  yet  his  keenest  sense  of  pleasure  came  from  the 
drinks  that  it  afforded.  These  he  had  in  almost  endless 
variety.  One  god  is  said  to  have  given  the  Mexicans 
nine  excellent  recipes  at  one  visitation.  Some  of  the 
drinks  were  nothing  more  than  thin  gruels  flavored  with 
salt,  pepper,  cacao,  or  herbs,  or  sweetened  with  honey 
or  with  the  juice  of  green  cornstalks.  Others  were 
fermented.  No  method  of  distillation  seems  to  have 
been  known,  and  the  alcoholic  content  of  these  drinks 
must  have  been  low;  but  a  few  were  so  strong  that  their 
use  was  forbidden,  except  on  very  special  occasions. 
The  most  popular  of  the  fermented  drinks  was  chicha, 
which  was  widely  known  in  many  forms.  It  was  pre- 
pared in  a  variety  of  ways,  the  dry,  parched,  or  sprouted 
grain  being  ground  or  masticated  and  then  mixed  with 
water  and  allowed  to  ferment. 

A  long-continued,  exclusive  diet  of  maize  always  leads 
to  digestive  disorders,  and  the  Indian  found  that  the  objec- 
tionable feature  was  removed  by  mixing  with  the  food 
some  substance  affording  a  chemical  or  mechanical 
irritant  to  act  as  a  stimulant.  This  is  said  to  have  been 
the  cause  of  the  popularity  of  the  chili  pepper  in  Mexico. 
Powdered  limestone,  clay,  or  saltpeter  was  used  for 
the  same  purpose;  and,  in  some  parts  of  South  America, 
ants  were  mixed  with  the  food,  their  chitinous  shells  and 
the  formic  acid  of  their  bodies  doubtless  having  the 
desired  effect.' 

'  Payne  (116),  pp.  406-7. 


212  THE  STORY  OF  THE  MAIZE  PLANT 

The  New  World  afforded  no  greater  delicacy  than 
the  green  ear  of  corn,  the  "  roasting  ear  "  of  modern  times. 
In  season  this  was  a  favorite  food  everywhere.  It  was 
eaten  raw,  boiled,  or  roasted;  and  the  Indian  was  the 
inventor  of  the  mixture  of  green  corn  and  beans  known 
as  "succotash."  The  juice  of  the  stem,  especially  in 
subtropical  climates,  was  often  extracted  and  boiled  down 
to  a  syrup,  or  fermented  and  used  as  a  drink. 

In  Mexico  and  some  other  parts  of  America,  corn  was 
regularly  depended  upon  for  a  part  of  the  food  supply  of 
the  flocks  of  domesticated  ducks,  geese,  and  turkeys; 
but,  with  the  exception  of  the  llama  and  its  relatives  in 
South  America,  there  was  no  domesticated  animal  for 
which  the  fodder  of  the  plant  might  furnish  food.  The 
stalks,  leaves,  and  husks  were  usually  wasted  except  for 
the  limited  use  that  was  made  of  them  for  mats,  beds, 
thatching,  or  fuel.  The  silks  of  the  plant  and  the  ashes 
of  the  cobs  were  supposed  to  have  medicinal  values. 

Maize  and  religion. — The  Indian's  religion  was  closely 
linked  with  his  daily  life.  His  gods  were  personifica- 
tions of  the  natural  forces  that  he  saw  at  work  about 
him,  and  at  whose  mercy  he  felt  himself  to  be.  A  pious 
attitude,  therefore,  was  good  poHcy,  for  it  was  likely  to 
win  for  him  the  good  will  of  the  powers  that  shaped  his 
environment. 

Since  maize  was  one  of  his  greatest  blessings,  it  must 
itself  be  the  work  of  a  deity,  but  many  other  deities  were 
necessarily  connected  with  its  existence.  Consequently, 
parts  of  the  maize  plant,  and  symbolical  idols  designed 
after  parts  of  it,  played  important  parts  in  the  numer- 
ous ceremonies  connected  with  the  manipulation  of 
the  crop. 


MAIZE  IN  ABORIGINAL  AMERICA  213 

In  most  localities,  the  maize  spirit  was  a  woman,  the 
maize-mother.  She  received  much  attention  in  religious 
ceremonies,  and  many  offerings  were  placed  on  her 
altar.  But  her  power  as  a  deity  was  thought  to  be 
limited;  she  was  dependent  upon  both  the  sun-god  and 
the  rain-god  for  the  success  of  her  work.  The  only 
idol  of  the  ancient  Mexicans  that  survived  the  foolish 
fanaticism  of  the  early  missionaries  in  that  country  is  a 
basalt  image  of  this  goddess.' 

The  charms  that  were  practiced  and  the  rites  that 
were  performed  to  protect  the  crop  are  exemplified  in 
"  The  Song  of  Hiawatha."  Inaccuracies  in  the  historical 
account  upon  which  Longfellow  based  this  poem  are 
responsible  for  certain  errors  of  detail,  but  the  spirit  of 
the  Indian's  respect  for  the  plant  is  faithfully  shown. 

Three  incidents  in  the  life  of  the  corn  plant  were 
celebrated  with  especially  elaborate  ceremonies  in  differ- 
ent parts  of  America.  These  were  the  germination  of 
the  seeds,  the  formation  of  the  ear,  and  the  harvest. 
The  first  two  of  these,  coming  at  critical  times  in  the 
activity  of  the  plant,  took  the  nature  of  propitiatory 
offerings.  The  last  was  more  on  the  order  of  a  thanks- 
giving. 

In  Peru,  the  time  between  planting  and  the  appear- 
ance of  the  plants  above  ground  was  a  time  of  fasting 
for  all  classes.  Boiled  maize  and  herbs  were  the  only 
foods  allowed,  and  strict  limitations  were  placed  upon 
the  drinking  of  fermented  liquors.  The  same  ceremony 
took  on  a  more  elaborate  form  in  Mexico.  Offerings  of 
corn  and  small  animals  were  made  to  the  maize-goddess 
and  her  associates,  especially  the  rain-goddess,  whose 
'  Payne  (116),  p.  469. 


214  THE  STORY  OF  THE  MAIZE  PLANT 

help  seems  to  have  been  much  needed.  Houses  were 
elaborately  decorated,  and  sham  battles  were  staged  in 
the  temple  of  the  goddess  of  harvests. 

The  Mexican  rites  of  "the  long-haired  mother"  came 
at  the  time  of  the  formation  of  the  ear  on  the  corn  plant 
and  lasted  eight  days.  It  took  the  form  of  a  dance 
beginning  at  the  end  of  each  day.  The  principal  part 
of  the  ceremony  was  a  dance  performed  by  the  women, 
who  shook  and  tossed  their  hair  in  imitation  of  the  silks 
of  corn.  A  prominent  figure  among  the  dancers  was  a 
slave  girl  dressed  and  painted  in  imitation  of  the  corn 
plant.  It  is  doubtful  if  she  was  allowed  to  know  the 
conclusion  of  the  ceremony,  for  she  was  intended  as  a 
sacrifice  to  the  maize-mother,  and  the  success  of  the 
whole  procedure  depended  upon  the  vigor  with  which 
she  danced  and  the  pleasure  that  she  derived  from  the 
occasion.  On  the  last  night,  the  dance  lasted  till  day- 
break, when  the  chiefs  and  warriors  appeared  on  the 
scene,  and  all  danced  the  death  dance.  Then,  in  a 
solemn  procession,  they  all  moved  to  the  teocalli  and 
killed  the  victim,  offering  her  heart  to  the  maize-mother. 
Until  this  rite  had  been  concluded,  "no  one  might  eat 
of  the  principal  luxury  of  the  New  World,  the  sweet, 
green  ear  of  maize;  for  the  corn  in  that  case  would  have 
failed  to  ripen.'" 

The  harvest  celebration  is  illustrated  by  a  custom  of 
the  Zapotecs  of  Mexico.  At  harvest  time,  the  whole 
population  went  in  ceremonial  procession  to  the  maize 
fields,  where  the  finest  ear  was  selected.  This  was  taken 
to  the  temple,  and,  after  a  sacrifice  to  the  harvest-god, 
it  was  carefully  wrapped  and  kept  till  planting  time. 
'  Payne  (ii6),  pp.  464-69. 


MAIZE  IN  ABORIGINAL  AMERICA  215 

Then  another  procession  was  formed,  and  the  ear  was 
taken  back  to  the  field  and  buried  in  a  specially  prepared 
pit,  while  sacrifices  were  being  offered.  Immediately- 
after  this,  planting  began.  As  harvest  time  approached 
again,  the  priests  went  once  more  to  the  field  and  dug 
up  the  buried  ear  and  distributed  the  grains  among  the 
people  as  talismans.  This  idea  in  keeping  the  best  ear 
buried  in  the  field  was  to  exert  a  good  influence  upon  the 
growing  crop. 

In  the  sacred  architecture  and  art  of  the  Indians, 
maize  had  a  deserving  place  of  prominence,  being  both 
artistic  and  worthy  of  veneration.  The  best  examples 
of  this  use  of  the  plant  were  found  in  the  temple  at 
Cuzco,  the  most  magnificent  in  Peru.'  This  temple  was 
elaborately  decorated  in  gold,  silver,  and  precious  stones. 
On  the  floor  of  the  great  salon  were  twelve  immense 
silver  vases  filled  with  corn.  The  old  Spanish  account 
says  that  these  were  as  high  as  a  good  lance  and  so  large 
that  two  men  with  outstreched  arms  could  hardly  reach 
around  them.  In  the  gardens  around  the  temple  only 
gold  and  silver  implements  were  used  in  tilling  the  corn. 
Inside  the  temple  was  a  garden  filled  with  life-size  maize 
plants  made  of  gold  and  silver. 

The  myths  and  legends  of  this  primitive  people 
centered  around  the  corn  plant  might  be  multiplied 
almost  without  limit,  as  might  also  the  accounts  of  the 
religious  rites  and  works  of  art  and  architecture  inspired 
by  the  plant,  for  every  tribe  had  its  own  characteristic 
traditions,  works,  and  practices.  But  a  more  detailed 
account  soon  involves  repetition,  and  the  Indian  instead 
of  corn  is  likely  to  become  the  chief  center  of  interest. 

'  Prescott  (120),  pp.  101-2. 


2i6  THE  STORY  OF  THE  IMAIZE  PLANT 

After  all,  the  theme  involved  throughout  is  a  simple 
one,  being  the  reaction  of  a  simple  intellect  toward  a 
fundamental  factor  of  its  environment. 

Americans  gift  to  mankind. — The  years  have  rolled 
away  since  first  the  white  man  reached  this  shore  of  the 
Atlantic,  and  the  Indian  race  as  a  race  will  soon  be  no 
more.  Did  Europe  interrupt  in  America  a  budding 
drama,  or  had  the  climax  been  reached  and  passed  ? 
As  a  consequence  of  the  part  that  we  have  played,  we 
like  to  believe  it  was  the  latter;  and  the  limitations  of 
the  red  race  and  their  environment  strengthen  our  behef . 
But  now,  that  he  is  passing  from  the  scene,  what  has 
been  the  Indian's  contribution  to  civilization?  To  the 
Latin  he  gave  some  gold  and  silver;  to  the  Anglo-Saxon, 
food  and  shelter  until  his  colony  was  firmly  rooted;  and 
he  enriched  the  languages  of  Europe  with  a  few  new 
terms,  and  her  literature  with  a  few  new  elements  of 
imagery;  but  his  great  and  enduring  gift  to  the  whole 
world  was  maize.  This  plant  he  took  from  vegetable 
barbarism  and  made  of  it  the  aristocrat  of  the  cereals; 
and  today  it  feeds  a  large  proportion  of  the  world's 
population,  and  is  the  basis  of  the  life  and  prosperity 
of  the  great  nations  of  America  as  truly  as  it  ever  was  in 
the  brightest  days  of  Aztec  or  of  Inca. 


CHAPTER  XXVII 
MAIZE  IN  AMERICAN  LIFE 

The  spirit  of  a  nation,  as  expressed  in  its  manners, 
customs,  arts,  and  literature,  necessarily  bears  a  strong 
imprint  of  the  leading  ways  that  its  citizens  have  of 
turning  natural  resources  into  the  necessities  and  luxuries 
of  daily  life.  As  a  factor  in  the  economic  life  of  the 
greatest  of  the  nations  that  have  grown  up  in  the  home- 
land of  maize,  this  plant  and  the  industries  that  are 
based  upon  it  are  of  supreme  importance.  It  is  but  a 
fulfilment  of  our  expectations,  then,  to  find  on  analysis 
of  our  modern  national  life  that  the  maize  plant  is 
inseparably  interwoven  into  the  spirit  of  America. 

Three  hundred  years  ago,  on  the  inhospitable  shores 
of  New  England,  it  began  its  career  of  Americanization. 
Winter  was  coming  on,  and  the  Mayflower's  suppHes 
were  low;  the  great  venture  promised  to  end  in  dismal 
failure.  But  the  discovery  of  an  abandoned  store  of 
Indian  corn  saved  the  colony  from  extinction;  and  the 
following  season  the  colonist  was  able  to  produce  a 
harvest  of  maize  so  bountiful  that  it  insured  the  success 
of  his  project.  We  shall  never  know  how  prominently 
the  name  of  maize  figured  in  the  Pilgrim's  prayers  on 
the  occasion  of  that  first  Thanksgiving. 

As  an  agricultural  achievement,  the  success  of  the 
Plymouth  colony  this  first  year  is  unparalleled  in  history. 
In  a  new  country,  where  the  soil  was  mediocre  and  the 
cHmate  strange,  the  Puritan  planted  a  crop  whose 
ways  he  httle  knew,  and,  with  only  a  savage  for  his 
217 


2i8  THE  STORY  OF  THE  MAIZE  PLANT 

teacher,  he  learned  his  lesson  in  agriculture  and  i)ut 
it  into  practice  so  effectively  that  his  results  eclij)sed 
the  best  that  he  had  ever  been  able  to  do  in  England. 
As  news  of  successes  like  this  made  its  way  back  to 
Europe,  there  began  to  appear  before  the  eyes  of  the 
oppressed  a  vision  of  America  as  the  land  of  opportunity. 

On  down  through  the  years  of  colonial  life,  and 
through  the  period  of  expansion  and  development  of 
the  young  republic,  maize  has  continued  to  be  the  key 
to  opportunity.  It  grew  luxuriantly  with  little  prepara- 
tion of  the  soil  and  little  cultivation;  its  growing  season 
was  marked  by  no  extremely  rigorous  climatic  conditions; 
and  it  had  few  enemies  that  could  not  successfully  be 
avoided.  It  was  an  ideal  crop  for  the  conditions,  promis- 
ing almost  certain  results  to  the  man  who  could  not 
afford  to  take  a  chance. 

The  grower  of  maize  is  today  in  a  position  to  enjoy 
a  large  degree  of  economic  independence.  The  product 
of  his  labor  can  be  turned  into  meat,  bread,  poultry, 
or  dairy  products  without  leaving  the  farm  and  with  the 
minimum  of  dependence  upon  other  industries.  The 
many  uses  to  which  corn  and  its  farm  products  can  be 
put,  and  the  consequent  independence  that  may  be 
exercised  in  disposing  of  the  crop,  greatly  increase  the 
difficulty  of  the  speculator  who  attempts  to  manipulate 
prices,  and  insures  a  relatively  advantageous  market 
condition. 

Mention  of  the  Corn  Belt  suggests  large,  prosperous, 
well-stocked  farms,  substantial  buildings,  good  roads, 
good  schools,  churches,  colleges,  and  universities,  and 
clean,  orderly  towns  and  cities  as  commercial  centers. 
It  is  a  land  of  prosperity,  intelligence,  and  contentment. 


MAIZE  IN  AMERICAN  LIFE  219 

Many  of  these  blessings  may  be  attributed  to  the  innate 
temper  of  the  pioneers  in  this  region,  but  to  the  pecuHar 
requirements  and  advantages  of  the  corn  industry  must 
go  much  credit  for  the  qualities  that  make  the  Middle 
West  the  embodiment  of  the  best  that  there  is  in  the 
ideal  Americanism. 

Certain  steps  in  the  manipulation  of  the  crop  have 
contributed  to  the  long  list  of  social  occasions  that  have 
had  so  much  to  do  with  the  shaping  of  American  ideals. 
In  earlier  days  the  logrollings  and  quilting  bees  were 
varied  in  season  with  an  occasional  husking  bee.  Some 
corn  was  usually  husked  on  these  occasions,  but  this 
was  not  necessarily  all  the  good  that  came  out  of  the 
event.  It  afforded  one  of  the  few  opportunities  in  those 
days  for  social  intercourse  and  fostered  the  formulation 
and  development  of  fundamental  political  and  economic 
policies.  Many  a  colonial  romance,  too,  had  its  begin- 
ning in  the  finding  of  a  red  ear  of  corn  by  some  novice 
too  timid  to  make  a  start  unaided.^ 

The  maize  plant  has  thus  far  inspired  few  works  of 
art,  literature,  or  architecture,  but  these  fields  ofiev 
promising  possibilities.  These  are  the  products  of  the 
maturity  of  a  nation,  and  America  is  still  in  the  period 
of  growth  and  development.  The  beauties  of  her 
resources  will  make  their  best  appeal  felt  only  after  the 
chmax  of  economic  development  has  been  passed.    The 

'  In  the  early  New  England  husking  bees  it  was  the  privilege  of  the 
youth  who  found  a  red  ear  of  com  to  kiss  any  girl  that  he  might  choose 
from  those  present;  and,  if  we  are  to  believe  the  stories  of  the  time,  it 
was  no  uncommon  thing  for  a  red  ear  once  found  to  be  hidden  in  the  pile 
of  unhusked  ears  and  repeatedly  rediscovered  and  used.  Imagination 
can  picture  the  opportunity  lost  through  a  lack  of  understanding  in  those 
days  of  the  manner  of  inheritance  of  the  red  pericarp. 


2  20  THE  STORY  OF  THE  MAIZE  PLANT 

utilitarian  bent  is  conducive  to  the  exercise  of  a  single- 
track  mind,  which  is  often  intolerant  of  a  search  for 
beauty  or  truth  in  a  place  where  usefulness  is  usually 
sought. 

Maize  has  ornamental  properties  that  will  in  time 
give  it  a  place  in  decorative  work.  It  has  already  been 
utilized  in  the  commercial  world  in  this  way,  having 
been  worked  into  some  attractive  advertising  designs. 
In  fairs  and  expositions,  also,  the  ears  and  grains  have 
been  effectively  used  in  symbolical  decoration. 

The  most  magnificent  examples  of  the  latter  ever 
attempted  were  the  corn  palaces  constructed  in  Iowa 
during  the  closing  years  of  the  past  century.  The  idea 
of  these  works  originated  in  Sioux  City,  and  those  built 
there  in  successive  years  from  1887  until  1895,  or  later, 
attracted  wide  attention  and  were  copied  in  many 
other  cities,  but  only  in  miniature  (see  Fig.  174). 

A  large  building,  100  to  250  feet  square,  with  elaborate 
gables,  domes,  towers,  and  pinnacles,  some  of  the  latter 
more  than  150  feet  tall,  was  constructed  of  wood  and 
then  completely  covered  with  ears,  stalks,  husks,  and 
grains  of  corn,  and  with  parts  of  other  agricultural  plants, 
arranged  in  attractive  designs.  In  some  instances, 
elaborate  designs  representing  farm  scenes,  nursery 
tales,  and  landscapes  were  worked  out  in  grains  of 
different  colors.' 

Such  works  as  these  silently  testify  to  the  place 
that  the  plant  holds  in  the  life  of  the  people  in  the  heart 
of  the  corn  country;  but  they  still  bear  the  stamp  of 
commercialism,  and  fade  into  insignificance  as  works  of 
art  when  compared  with  the  symbolical  ornamentation 

I  Plumb  (iiS),  pp.  230-32. 


MAIZE  IN  AMERICAN  LIFE 


of  the  ancient  Inca  Temple  of  the  Sun.'  The  inspiration 
of  a  modern  work  of  art  that  will  be  an  appreciation  of 
maize  for  its  aesthetic  value  alone  belongs  to  the  days 
that  are  yet  to  come.  The  poet  and  the  essayist  have 
made  more  extended  use  of  the  material  offered  them, 


Fig.  174. — A  com  palace  built  at  Sioux  City  in  li 
by  permission  of  the  Breeders'  Gazette). 


(after  Plumb, 


and  the  Hterature  of  the  world  is  richer  by  many  a  gem 
whose  theme  is  the  sentimental  appeal  of  maize.  Both 
the  lore  of  the  Indian  and  the  beauty  and  fragrance  of 
the  prairie  cornfield  of  today  have  done  their  part  in 
the  way  of  inspiration. 

In  the  well-known  "Song  of  Hiawatha,"  Longfellow 
has  immortahzed  many  sketches  of  the  life  of  the  North 

'  See  p.  215;  also  Prescott  (120),  pp.  101-2. 


2  22  THE  STORY  OF  THE  MAIZE  PLANT 

American  Indian.  Among  these  is  an  account  of  the 
manipulation  of  the  maize  crop  by  Hiawatha,  the 
mythical  hero  of  the  tribes  of  the  Eastern  United  States. 
Here  unfolds  a  vivid  picture  of  the  preparation  of  the 
soil,  the  planting  and  tillage  of  the  crop,  and  the  festivi- 
ties of  the  harvest,  and,  accompanying  all  these  activities, 
the  rites  and  ceremonies  designed  to  charm  away  the 
enemies  of  the  plant. 

Bayard  Taylor's  "Mondamin"  pictures  the  coming 
of  the  maize  deity,  Mondamin,  to  the  Ojibways  of  the 
Great  Lakes  region.^  Osseo,  an  Indian  Prince,  while 
undergoing  a  religious  fast,  is  visited  by  Mondamin  in 
the  guise  of  a  youth  dressed  in  brilhant  green  and 
adorned  with  waving  plumes.  On  six  successive  days 
the  two  test  their  strength  in  a  friendly  wresthng  bout, 
and,  before  the  seventh  test,  the  god  foretells  his  own 
defeat  and  directs  Osseo  to  bury  him  in  the  earth  when 
he  has  been  vanquished.  The  prince  follows  the  instruc- 
tions and  is  rewarded  in  due  time  with  the  first  corn 
plant  the  tribe  has  ever  seen.  To  the  Indian  each  new 
season's  wrestle  with  the  difficulties  of  producing  a  crop 
was  a  pageant  representation  of  this  mythical  struggle; 
and  the  poet,  carrying  the  figure  down  to  the  present, 
sees  Mondamin  still  in  our  cornfields.  And,  although 
many  times  dead  and  buried  in  the  ground, 

Mondamin  remained,  and  still  remains; 
His  children  cover  all  the  boundless  land, 

And  the  warm  sun  and  frequent  mellow  rains 

Shape  the  tall  stalks  and  make  the  leaves  expand. 

A  mighty  army  he  has  grown :  he  drills 
Their  green  battalions  on  the  summer  hills. 

'  Longfellow  also  gives  a  version  of  this  myth  with  Hiawatha  as  the 
human  hero  of  the  contest  with  Mondamin. 


MAIZE  IN  AMERICAN  LIFE  223 

And  when  the  silky  hair  hangs  crisp  and  dead, 
Then  leave  their  rustling  ranks  the  tasseled  peers, 

In  broad  encampment  pitch  their  tents  instead 
And  garner  up  the  bright  autumnal  ears; 

The  annual  storehouse  of  a  nation's  need, 

From  whose  abundance  all  the  world  may  feed. 

The  "Corn  Song,"  of  Godfrey  Marks,  has  been  set 
to  music  and  holds  a  merited  place  in  the  public-school 
music  of  many  sections  of  the  Middle  West. 

Whittier,  whose  word  pictures  of  early  New  England 
country  life  will  live  forever,  puts  into  verse  now  and 
then  the  sentiment  of  the  husking  bee  or  scenes  in  the 
home  or  camp,  where  the  pioneer  partakes  of  his  simple 
fare,  largely  the  product  of  the  maize  plant,  "The 
Huskers"  closes  with  that  well-known  lyric,  "The 
Corn  Song." 

Edward  Everett  selected  a  fitting  subject  for  his 
eloquence  when  he  said : 

Drop  a  grain  of  our  gold,  of  our  blessed  gold,  into  the  ground, 
and  lo!  a  mystery;  it  softens,  it  swells,  it  shoots  upward;  it  is  a 
living  thing;    it  arrays  itself  more  glorious  than  Solomon  in  its 

broad,  fluttering,  leafy  robes It  spins  its  verdant  skeins 

of  vegetable  floss,  displays  its  dancing  tassels;  and  at  last  ripens 
into  two  or  three  magnificent  batons,  each  of  which  is  studded 
with  hundreds  of  grains  of  gold,  every  one  possessing  the  same 
wonderful  properties  as  the  parent  grain,  every  one  instinct  with 
the  same  marvellous  reproductive  powers. 

To-day  a  senseless  plant,  to-morrow  it  is  human  bone  and 
muscle,  vein  and  artery,  sinew  and  nerve,  beating  pulse,  heaving 
lungs,  toiling  brain.  Heaped  in  your  granaries  this  week,  the 
ne.xt  it  will  strike  in  the  stalwart  arm,  and  glow  in  the  blushing 
cheek,  and  flash  in  the  beaming  eye;  till  we  learn  at  last  to  realize 
that  the  slender  stalk  that  we  have  seen  shaken  by  the  summer 
breeze,  bending  in  the  cornfield  under  the  yellow  burden  of  harvest. 


224  THE  STORY  OF  THE  MAIZE  PLANT 

is  indeed  the  "staff  of  life,"  which  since  our  nation's  earliest  history- 
has  supported  the  toiling  and  struggling  masses  on  the  pilgrimage 
of  existence.' 

Out  of  the  enthusiastic  interest  in  the  adoption  of  a 
national  flower  on  the  occasion  of  the  four  hundredth 
anniversary  of  the  discovery  of  America,  there  came  a 
number  of  tributes  to  the  maize  plant.^  These  should 
arouse  in  every  American  a  little  deeper  feeling  than  for 
mere  physical  hunger  satisfied. 

A  poem  of  this  period,  doubtless  the  most  fitting 
appreciation  that  we  have  of  this  plant  most  eminently 
qualified  to  become  the  nation's  emblem,  is  a  fitting 
conclusion. 

Blazon  Columbia's  emblem, 

The  bounteous  golden  corn! 

Eons  ago  of  the  great  sun's  glow 

And  the  joy  of  the  earth  'twas  bom. 

From  Superior's  shore  to  Chile, 

From  the  ocean  of  dawn  to  the  west. 

With  its  banner  of  green  and  silken  sheen 

It  sprang  at  the  sun's  behest; 

And  by  dew  and  shower  from  its  natal  hour 

With  honey  and  wine  'twas  fed 

Till  the  gods  were  fain  to  show  with  men 

The  perfect  feast  outspread; 

For  the  harvest  boon  to  the  land  they  loved 

Was  the  corn  so  rich  and  fair. 

Nor  star  nor  breeze  o'er  the  farthest  seas 

Could  find  its  like  elsewhere. 

'  In  response  to  a  toast  at  a  dinner  of  the  United  States  Agricultural 
Society,  1855. 

=  See  the  symposium  on  maize  as  the  national  flower  in  The  Arena, 
VIII  (1893),  92-114. 


MAIZE  IN  AMERICAN  LIFE  225 

In  their  holiest  temples  the  Incas 
Offered  the  heaven  sent  maize, 
Grains  wrought  of  gold  in  a  silver  fold 
For  the  sun's  enraptured  gaze, 
And  its  harvest  came  to  the  wandering  tribes 
As  the  god's  own  gift  and  seal; 
And  Montezuma's  festal  bread 
Was  made  of  its  sacred  meal. 
Narrow  their  cherished  fields,  but  ours 
Are  broad  as  the  Continent's  breast. 
And  lavish  as  leaves  the  rustling  sheaves 
Bring  plenty  and  joy  and  rest; 
For  they  strew  the  plains  and  crowd  the  wains 
When  the  reapers  meet  at  morn. 
Till  the  blithe  cheers  ring  and  west  winds  sing 
.  A  song  for  the  garnered  corn. 

The  rose  may  bloom  for  England, 

The  lily  for  France  unfold, 

Ireland  may  honor  the  shamrock 

And  Scotland  her  thistle  bold; 

But  the  shield  of  the  Great  Republic, 

The  glory  of  the  west, 

Shall  bear  a  stalk  of  the  tasseled  corn, 

Of  all  her  wealth  the  best. 

The  arbutus  and  the  golden  rod 

The  heart  of  the  north  may  cheer, 

And  the  mountain  laurel  for  Maryland 

Its  royal  clusters  rear. 

And  jasmine  and  magnolia 

The  crest  of  the  south  adorn; 

But  the  wide  Republic's  emblem 

Is  the  bounteous  golden  corn.' 

'  Columbia's  Emblem,"  by  Edna  Dean  Proctor. 


FItOFERTY  USURY 
N.  C.  State  College 


BIBLIOGRAPHY 

A  complete  bibliography  of  this  subject  would  in  itself  fill 
many  volumes.  The  references  listed  here  are  intended  merely 
to  direct  the  reader  to  more  detailed  treatments  of  the  various 
topics,  and  to  cite  the  sources  of  many  points  of  unusual  interest. 

1.  Anderson,  E.  G.,  "The  Inheritance  of  Salmon  Silk  Color  in 

Maize,"  Cornell  Agric.  Exper.  Sta.  Memoir  48,  1921. 

2.  Andrews,  A.  Leroy,  "Philological  Aspects  of  the  'Plants  of 

Wineland  the  Good,'"  Rhodora,  XV  (1913),  28-35. 

3.  Andronescu,  D.  I.,  The  Physiology  of  the  Pollen  of  "Zea 

Mays"  with  Special  Regard  to  Its  Vitality,  191 5. 

4.  Atkinson,  A.,  and  Wilson,  M.  L.,  "Corn  in  Montana," 

Montana  Agric.  Exper.  Sta.  Bull.  107,  19 15. 

5.  Bancroft,  H.  H.,  The  Native  Races,  Vol.  II,  1883. 

6.  Blaringhem,  L.,  Mutation  ct  tratimatismes,  1907. 

7.  Blakeslee,  a.  F.,  "Corn  and  Education,"  Jour,  of  Heredity, 

VIII  (1917),  51-57- 

8.  Bollman,  Lewis,  "Indian  Corn,"  Indiana  State  Board  of 

Agric.  Rept.  (1856),  pp.  285-314. 

9.  BONAFOUS,  M.,  Histoire  natiirelle,  agricole,  et  economique  du 

Mats,  1836. 

10.  Bregger,  T.,  "Linkage  in  Maize:   The  C  Aleurone  Factor 

and  Waxy   Endosperm,"   A^ner.   Naturalist,    LII    (1918), 
57-61. 

11.  Brooks,  E.  C,  The  Story  of  Corn  in  the  Westward  Migration, 

1916. 

12.  Brown,  E.  B.,  and  Garrison,  H.  S.,  "Effect  of  Date  of 

Seeding  on   Germination,   Growth,   and  Development   of 
Corn,"  U.S.  Dept.  of  Agric.  Bull.  1014,  1922. 

13.  Bugnon,  p..  La  feuille  chez  les  Graminees,  1921. 

14.  BuRLisoN,  W.  L.,  AND  White,  E.  A.,  "Selection  and  Storage 

of  Seed  Corn,"  Illinois  Agric.  Exper.  Sta.  Circ.  225,  1918. 

15.  Burtt-Davy,  Joseph,  Maize,  Its  History,  Cultivation,  Hand- 

ling, and  Uses,  1914. 

226 


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154.  Weatherwax,  Paul,  "  Gametogenesis  and  Fecundation  in 

Zea  Mays  as  the  Basis  of  Xenia  and  Heredity  in  the  Endo- 
sperm," Bull.  Torrey  Club,  XL VI  (1919),  73-90. 

155.  Weatherwax,  Paul,  "The  Ancestry  of  Maize— a  Reply 

to  Criticism,"  ibid.,  pp.  275-78. 


BIBLIOGRAPHY  235 

156.  Weatherwax,  Paul,  "A  Misconception  as  to  the  Structure 

of  the  Ear  of  Maize,"  ibid.,  XL VII  (1920),  359-62. 

157.  Weatherwax,  Paul,  "The  Origin  of  the  Intolerance  of 

Inbreeding    in    Maize,"    Amer.    Naturalist,    LIV    (1920), 
184-87. 

158.  Weatherwax,  Paul,  "The  Homologies  of  the  Coleoptile  and 

Position  of  the  Scutellum  in  Maize,"  Bot.  Gaz.,  LXIX 
(1920),  179-82. 

159.  Weatherwax,  Paul,  "The  Popping  of  Corn,"  Proc.  Indiana 

Acad.  Sci.for  ig2i  (1922),  pp.  149-53. 

160.  Weatherwax,   Paul,    "A   Rare   Carbohydrate   in   Waxy 

Maize,"  Genetics,  VII  (1922),  568-72. 

161.  Webber,  H.,  "Xenia,  or  the  Immediate  Effect  of  Pollen  in 

Maize,"  U.S.  Dept.   of  Agric,.  Div.  Veg.  Phys.  and  Path. 
Bull.  22,  1900. 

162.  Wenz,  Alfred,  "The  Heart  of  the  Corn  Country,"  Dakota 

Farmer,  XXXVI  (1916),  1068-70. 

163.  White,  O.  E.,  "Inheritance  of  Endosperm  Color  in  Maize," 

Amer.  Jour.  Bot.,  IV  (1917),  396-406. 

164.  Wilbert,  M,  I.,  "Why  Popcorn  Pops,"  Amer.  Jour.  Pharm., 

LXXV  (1903),  77-79. 

165.  Wiley,  H.  W.,  "  Composition  of  Maize,"  Bur.  Chem.  Bull.  50, 

1898. 

166.  Wilson,  G.  L.,  Agriculture  of  the  Hidatsa  Indians,  191 7. 

167.  Wissler,     Clark,     "Aboriginal     Maize     Culture     as     a 

Typical  Culture  Complex,"  Amer.  Jour.  Soc,  Vol.  XXI, 
1916. 

168.  Wissler,  Clark,  The  American  Indian,  191 7. 

169.  Wittmack,  L.,  "Ueber  antiken  Mais  aus  Nord-  und  Siid- 

amerika,"  Zeits.f.  Ethnol.,  XII  (1880),  85-97. 

170.  Wolfe,  T.  K.,  "Anomalous  Seeds  in  Zea  Mays,"  Virginia 

Agric.  Exper.  Sta.  Kept,  for  igij-igi6,  pp.  193-99. 

171.  Woods,  CD.,  "Food  Value  of  Corn  and  Corn  Products," 

U.S.  Dept.  of  Agric.  Farm.  Bull.  2g8,  191 5. 

172.  WoRSDELL,  W.  C,  "The  Morphology  of  the  Monocotyledo- 

nous  Embryo  and  That  of  the  Grass  in  Particular,"  ylim. 
Bot.,  XXX  (1916),  509-24. 


INDEX 


INDEX 


Abortion:  of  pistil,  ii6;  speciali- 
zation by,  26;  of  stamens,  117 

Acosta,  reference  to  work  of,  197 

Adaptation:  to  cross-pollination, 
130,  179;  to  length  of  season,  67, 
68 

Africa,  maize  in,  1 7 

Agricultural  varieties,  naming  of,  6 

Agriculture,  aboriginal,  based  upon 
maize,  198 

Albinism,  51,  177 

Alcohol,  193 

Aleurone:  layer,  155,  162,  163; 
mosaics,  156,  162,  163;  pig- 
ments, 155 

America,  maize  in  aboriginal,  12, 
13,  198,  199 

Anastomosing  of  vascular  bundles, 
42 

Ancestry  of  maize,  27-31 

Androgyny, 105,  108 

Andronescu,  reference  to  work  of, 
134 

Andropogoneae,  30 

Angoumois  grain  moth,  74 

Animals  as  an  ecological  factor,  70, 
71 

Anomalies:  in  the  flower,  1 17-19; 
general  occurrence,  24,  26;  in 
the  inflorescence,  103-7;  of 
sexuality,  103-6,  1 17-18;  in  the 
spikelet,  11 7-19 

Anthesis  in  the  tassel,  128 

Antipodal  tissue,  139 

Ants:  andaphids,  73;  and  pollina- 
tion, 127 

Aphids,  73 

Archaeological  remains  of  maize, 
23 

Archesporial  cell,  136 


Army  worm,  73 

Artistic  properties  of  maize,  220 
Asia,  maize  in,  16 
Auricles  of  leaf,  47 
Aztecs:  customs  and  traditions  of, 
214;  floating  gardens  of,  208 

Bacterial  wilt  diseases,  77 
Balanced  ration,  maize  in,  187,  196 
Bamboo,  leaf  of,  47,  48 
Bancroft,    reference    to    work   of, 

199,  200 
Bibliography,  226-35 
Bifurcate  ears,  107 
Billbug,  72 

Birds  as  an  ecological  factor,  71 
Blade  of  leaf,  47-52 
Blakesiee,  reference  to  work  of,  152 
Bonafous,  reference  to  work  of,  18 
Borers,  72 
Brace  roots,  64 
Branch  corn,  106,  107,  109 
Branched  ears,  56,  58,  106,  107 
Breeding:   benefits  from,  182;   by 

hybridization,  183;    importance 

of,  181;    methods  of,  182,  183; 

plat,  182,  185;  problems  of,  185; 

by  selection,  182 
Buds:  in  axils  of  husks,  57,  59;  at 

nodes,  40,  56 
Budworms,  72 
Burbank    on     the     evolution     of 

maize,  27 
Buttress  roots,  64 

Canari  tradition,  200 
Cane  sugar  from  corn,  193 
Capillarity  and  cultivation,  89 


239 


240 


THE  STORY  OF  THE  MAIZE  PLANT 


Carbohydrates:  in  the  endosperm, 
156;  formation  of,  by  photo- 
synthesis, 53.  54;  transforma- 
tion of,  in  the  endosperm,  159, 
160 

Carbon  bisulphide  fumigation,  75 

Care  of  seed,  83 

Caryopsis:  character  of,  163-68; 
fruit  of  grasses,  145;  parts  of, 
31,  145,  146 

Cates,  reference  to  work  of,  88 

Central  America,  origin  of  maize 
in,  20 

Charred  remains  of  maize,  23 

Checkrowing:  advantages  of,  87; 
cultivation  following,  87;  meth- 
od of,  85-87 

Chemical  nature  of  endosperm, 
156-60 

Chic  ha,  211 

Chili  pepper,  use  of  in  Mexico,  211 

Chinch  bug,  72 

Chinch-bug  fungus,  76 

Chinese  origin  of  maize,  18,  19; 
variety  of  maize,  19,  156 

Chionachne,  8 

Chloroplasts:  of  bundle  sheath  of 
leaf,  52;  of  mesophyll,  50 

Chromosomes,  number  of,  133 

Cigarette  wrappers  from  corn 
husks,  195 

Civilization  of  the  Indian,  196, 
198,  199 

Classification:  based  upon  monoe- 
cism,  7;  of  maize,  7 

Climate  as  an  ecological  factor,  66 

Cob:  ashes  of,  195;  chemical 
analysis  of,  195;  color  of,  144; 
definition  of,  140;  maple  sub- 
stitute from,  195;  pipes  made 
from,  195;  structure  of,  140; 
uses  of,  195 

Coix,  8 

Coleoptile:  general  nature,  32,  33; 
origin,  148;  rupture  of,  in 
germination,  35 


Coleorhiza:     general    nature,    32; 

origin,     148;      rupture     of,     in 

germination,  35 
Collins,  reference  to  work  of,  19, 

23,  29,  36,  III,  112 
Colors:      of    aleurone,     155;      of 

caryopsis,     168;      of     corneous 

endosperm,  157;  of  maize  known 

to    the    Indians,    155,    171;     of 

parts  of  the  leaf,  50,  51 
Columbus'  discovery  of  maize,  12 
Common  names  of  maize,  4,  5 
Compound  grains,  166 
Compound  spikelets,  118,  119 
Conservation  of  moisture  in  culti- 
vation, 88,  89 
Corn  Belt  prosperity,  218 
Corn:  judging,  141-44;   meanings 

and  applications  of  the  term,  4, 

S;  palaces,  220;  planters,  85 
Corneous  endosperm,  157 
Correns,  reference  to  work  of,  168, 

169 
Cotyledon:    an   absorbing  organ, 

38;    enzymes  produced  by.  38; 

position  of ,  3 1 ,  3  2 ;  rudimentar>', 

33 
"Country  Gentleman"  sweet  corn, 

119,  141,  166,  167 
Critical  periods  in  the  life  of  the 

plant,  68,  91,  213 
Cross-pollination:    extent  of,  131; 

and  hybrid  vigor,  130,  176-79 
Cultivation,  S8-92,  204 
Cutting  corn,  94-96 
Cutworms,  damage  done  by,  72 

Damping-off  disease,  76 

Dent  corn,  142,  159,  160,  167 

Depth  of  planting,  36 

Determinate  nature  of  spikelet, 
"5 

Development:  of  embryo,  147, 
148;  of  embryo  sac,  136-39;  of 
endosperm,  153;  of  flower,  120, 
121;  of  ovule,  125;  of  pistil,  122, 


INDEX 


241 


123,   139;    of  spikelet,   119-24; 

of  stamen,  121;  of  stem,  44-46 
Dextrins,  156,  159,  190 
Dichogamy,  130 
Dioecism,  tendency  toward,  104 
Disorganization  of  megaspores,  138 
Distichism    in    structure    of    the 

plant,  7,  no 
Distribution  of  maize:   aboriginal, 

198,    199;    agencies  of,   66;    in 

America  at  present,  15,  16;    in 

other  countries,  15,  16 
Double    fecundation:     occurrence 

of,  139;  and  xenia,  173 
Drought,  effects  of,  52,  53,  68 
Dudley,  reference  to  work  of,  172 
Dust  mulch,  89 

Ear-bearing  branch,  56-58 

Ear:  secondary  buds  of,  57,  58; 
decay  of,  77;  origin  of,  no; 
size  and  shape  of,  142,  143 

Ear- worm,  73,  77 

Ecology  of  maize,  66-80 

Egypt,  ear  of  corn  said  to  have 
been  found  in  ancient  tomb,  17 

Embryo:  development,  147,  148; 
differentiation,  14S;  homologies 
of,  31,  32,  149;  origin  of,  147.; 
position  on  grain  and  on  ear, 
141;  suspensor  of,  148,  149 

Embryo  sac,  138 

Emerson,  reference  to  work  of,  155 

Endodermis,  61,  62 

Endosperm:  absorption  of,  38; 
chemical  nature,  156-62;  cytol- 
ogy, 154,  155;  development, 
154-55;  heredity  in,  170-76; 
hybrid  vigor  in,  165;  multiple 
factors  in,  174;  origin  of,  139, 
154;  physical  texture  of,  157; 
pigments,  155,  157;  protein  and 
starch  in,  156,  162;  reserve 
materials,  156-62;  significance 
of,  139,  i53>  154;  varieties 
based  upon,  142,  160;  xenia  in, 
170-73;  yellow  color  of,  157,  158 


Ensilage,  187 

Enzymes:     reversible    nature    of, 

192;  work  of,  38,  159,  160 
Epiblast  of  grasses,  S3 
Epicotyl,  elongation  of,  36 
Epidermis:    of  leaf,  49;    of  stem, 

40,  41 
Euchlaena:      distinguished     from 
Zea,     10;     distribution    of,    9; 
uses  of,  9 
Europe,  maize  in,  16 
Everett,  quotation  from,  223 
Evolution:    of  agriculture  in  an- 
cient America,  202;  of  maize,  26 
Excretion  by  roots,  64 

Fasciated  grains,  166 

Fasciation:  of  the  ear,  107;  origin 

of  the  ear  by,  no 
Fats:  in  the  embrj'o,  156,  189,  190; 

absent  from  the  endosperm,  156; 

formation  of,  54 
Fecundation,  139,  147 
Feeding  value  of  corn,  187,  196 
Fermented  products,  193 
Fertilization.     See  Fecundation 
Fibrous  nature  of  roots,  60 
Flake  hominy,  189 
Floating  gardens  of  the  Aztecs,  208 
Flour  from  maize,  1S9,  196 
Focke,  reference  to  work  of,  171 
Fodder,    value    of,    impaired    by 

weathering,  94 
Fodder-pulling,  97 
Fossil  parts  of  maize,  23 
Eraser,  reference  to  work  of,  99 
Frost,  effects  of,  67 
Fruit,  definition  of,  140 
Fruit:  the  caryopsis,  140,  145;  the 

ear,  140 
Fuel  value  of  maize,  194 
Fungous  disease  of  the  chinch  bug, 

76 
Fungous  diseases  of  maize,  66-80 


242 


THE  STORY  OF  THE  MAIZE  PLANT 


Fusion  of  spikes  to  form  the  ear, 
theory  of,  in 


Garden  beds,  207 

Genetics:     maize    in,    169,    170; 

origin  of  as  a  science,  169 
Geological  evidences  as  to  origin 

of  maize,  23 
Germination:    conditions  for,  35; 

duration  of,  38;   steps  in,  35-3S 
Gernert,  reference  to  work  of.  107 
Glucose,  190,  191 
Glumes,  114-20 
Grading  of  seed,  84 
Grain  moth,  74 
Gramineae.     Sec  Grasses 
Grasses:    botanical  nature  of,   7; 

subdivisions  of,  7 
Grasshoppers,  damage  done  by,  73 
Gravity  as  an  agent  in  pollination, 

127 
Grits,  189 

Grooves  on  the  stem,  40 
Growing  season,  67 
Growth:    curvatures  of  stem,  46; 

of  stem,  16;  of  roots,  61 
Grubs,  damage  done  by,  7 1 
Guignard,  reference  to  work  of, 

139,  173 
Guttation,  55,  63 

Hackel's  theory  of  origin  of  the 

ear,  no 
Hail,  damage  done  by,  69 
Harshberger,  reference  to  work  of, 

13,  28,  29,  III 
Harvest  rites  of  Indian  tribes,  213, 

214 
Harvesting,  93-98,  209 
Heredity:  in  the  endosperm,  170- 

76;  maize  in,  169;  of  vegetative 

characters,  170 
Heterotypic  divisions,  133,  138 
Hiawatha,  legend  of,  213,  221,  222 


Hills:  effect  of  in  evolution,  131, 
205;  planting  in,  204,  205 

Hitchcock,  reference  to  work  of,  7 

"Hogging"  as  a  method  of  har- 
vesting, 93 

Hominy:  flake,  1S9;  grits,  189; 
lye,  189,  210 

Homologies:  of  embryo,  149;  of 
leaf,  47,  48;  of  pistillate  branch, 
110-13;  of  tassel,  110-13 

Human  sacrifice  to  the  maize 
deity,  214 

Husking  corn:  by  hand,  93,  94; 
by  machinery,  93,  96 

Husks:  buds  in  the  axils  of,  57; 
cigarette  wrappers  from,  195; 
homologies  of,  56,  57;  laminate, 
57;  uses  of,  195 

Hybrid  origin  of  maize,  theory  of, 
29 

Hybrid  vigor:  in  the  endosperm, 
165;  theories  of,  178,  179;  in 
vegetative  parts,  176-78,  183, 
184 

Hybridization:    in  breeding,   183; 

technique  of,  183 
Hybrids:    evidences  of  evolution 

from,   24;    between  maize  and 

teosinte,  24 

Hygroscopic  cells  of  the  leaf,  52,  53 

Implements  of  cultivation:  evolu- 
tion of,  90,  91;  modern,  91; 
used  by  the  Indian,  204,  206 

Indian  agriculture,  197-209 

Indian  corn,  a  common  name  for 
maize,  5 

Indian:  maize  deities,  212,  213; 
meaning  of  maize,  5;  myths  as 
to  the  origin  of  agriculture,  199- 
201;  names  for  maize,  4 

Indian  wheat  or  millcl,  names  for 
maize,  5 

Inflorescence:  anomalous,  104; 
mixed,  105,  106;  pistillate,  103; 
staminate,  100-102;  of  suckers, 
107-9 


INDEX 


243 


Insect  pests,  71-76 
Integuments,  125 
Internode,  section  of,  41 
Introduction  of  maize :  into  Africa, 

14;  into  Asia,  14;   into  Europe, 

12 
Irrigation:     in    Mexico,    209;     in 

Peru,  208,  209 
Iron   necessary   for   formation   of 

chlorophyll,  51 

"Job's  Tears,"  8 
Judging  of  corn,  141-44 

Kempton,  reference  to  work  of,  156 
Kiesselbach,  reference  to  work  of, 
52 

Lamina:   of  husk,  57;   of  leaf,  47, 

48 
Leaf:     food   value   of,    186,    187; 

parts    of,    47;     sheath,    46-48; 

uses  of,  186,  187 
Lemma,  114,  116-18,  120 
Ligule:    of   foliage   leaf,    53;     of 

husk,  57 
Liguleless  corn,  53 
Lindstrom,  reference  to  work  of,  51 
Linnaeus  names  maize,  5 
Listing  as  a  method  of  planting,  87 
Live  stock,  maize  as  food  for.  186, 

187 
Lobed  leaves,  48,  49 
Locusts.     See  Grasshoppers 
Lodicules,  114,  121,  122 
Longfellow,  poem  by,  221 
Lye  hominy,  189,  210 

"Maiz  de  coyote,"  28 

Maize  areas  in  aboriginal  .\merica, 

198,  199 
Maize  deities  of  the  Indians,  212, 

213 
Maize,  in  heredity,  169,  170 
Maize,  origin  of  the  word,  4 
Man  as  an  ecological  factor,  66 


Manufacture  of  products  from  the 

grain,  188-92 
Marks,  reference  to  poem  by,  223 
Maya   tradition   as   to   origin   of 

agriculture,  199,  200 
Maydeae.     See  Tripsaceae 
Mays,  spelling  and  capitalization 

of,  5 
Meal,  188 
Mealies,  5 
Meal-worm,  74 
Mechanical    advantages    of    stem 

structure,  40,  41 
Medicinal  uses:  of  corn  smut,  196; 

of  maize,  195 
Mendelism:    maize  in,   169,   170, 

origin  of,  169 
Megaspore  mother-cell,  136,  138 
Megaspores:     disorganization    of, 
138;    formation   of,    138;     ger- 
mination of,  138 
Mesophyll,  51,  52 
Metabolism,  53,  54 
Mexico,  maize  in,  198,  202 
Micropyle,  125 

Miles,  reference  to  work  of,  51 
Miller,  reference  to  work  of,  139 
Milling  processes,  188 
Mimicry  in  aleurone  colors,  156 
Moisture,  conservation  of,  88,  89 
Mondamin,  a  maize  deity,  222 
Monoecism:    a  criterion  of  classi- 
fication, 30;  in  maize,  69 
Montgomery,  reference  to  work  of, 

III 
Morphology  and  evolution,  30 
Mosaic  aleurone,  156,  162,  163 
Moulton,  reference  to  work  of,  27 
Mounds,  maize  from,  23,  34 
Mulch,  for  conserving  moisture,  89 
Multiple    factors    in    the    endo- 
sperm, 174-76 
Myths  as  to  the  origin  of  maize, 
199-201 


244 


THE  STORY  OF  THE  MAIZE  PLANT 


Names  of  maize:    popular,  4,   5; 

technical,  5 
Navajo  "sacred"  corn,  156,  163 
Navajo  tradition  as  to  origin  of 

maize,  200 
"Ne  plus  ultra"  sweet  corn,  119 
Non-Mendelian  views  of  heredity, 

179 
North  America,  maize  in,  13,  14 
Northmen  thought  to  have  seen 

maize,  11 
Nucellus,  125,  136 
Nuclear  divisions:    in  endosperm, 

154,  155;  in  spore  mother-cells, 

^33,  138 

Oil:  located  in  the  embryo,  189, 
190;  refinement  and  uses  of,  190 

Origin  of  the  ear  of  maize,  1 10-13 

Origin  of  maize:  botanical,  22-31; 
double,  19,  20;  place  of,  20; 
theories  of,  26-31 

Origin  of  maize  culture,  199 

Osmosis,  63 

Ovary,  development  of,  122,  123 

Ovule,  development  of,  124,  125 

Palea,  114,  1 16-18, 120 

Palmer,  reference  to  the  work  of, 
158 

Parenchyma  of  stem,  40,  41,  194, 
19s 

Pasturing  as  a  method  of  harvest- 
ing, 93,  94 

Payne,  reference  to  work  of,  200, 
203,  211,  213,  214 

Pedigree  breeding,  184 

Pentose  sugars,  195 

Perfect  flowers,  117 

Periblem,  61 

Pericarp:  colors  of,  151,  152; 
definition,  150;  effect  of,  on 
size  and  shape  of  grain,  164,  165; 
layers  of,  150;  special  pigment 
spot  of,  150,  151 


Peru,  maize  in,  208 
Peruvian   rites  at  planting   time, 
213 

Photosynthesis,  53,  54 

Physical  texture  of  endosperm,  157 

Phytomer    parts  of,  40,    the  unit 

of  structure,  40 
Pigmentation:  of  aleurone,  155, 
168;  of  corneous  endosperm, 
157,  158,  168;  dependent  upon 
light,  152;  of  pericarp,  151,  152, 
168 
Pistil:  origin  of,  122;  tricarpellarv 

nature,  125 
Pistillate:     branch,    56,    57;     in- 
florescence, 103,  105;    spDcelet, 
116 
Pith  of  stem,  uses  of,  194,  195 
Planting:    by   hand,    85;    Indian 
methods  of,  204 ;   by  machinery, 
85-87 
Plerome,  61 

Plumb,  reference  to  work  of,  221 
Plumule,  32,  S3,  U7,  14S 
Plumule  sheath.    See  Coleoptile 
Pod  corn:  bracts  of,  144,  145;  ear 
of,    143,    145;     not    a    distinct 
variety,  30;   tassel  of,  102,  105 
Poetry  on  corn,  221-25 
Poisoning  of  live  stock  by  smut,  79 
Pollen:  abundance  of,  129;  grain, 
^33,  134;  grain,  germination  of, 
124,     135;      mother-cell,     133; 
tube,  course  followed  by,   123; 
tube,  development  of,  70,   124, 
134 
Pollination:     agencies   of,    69;     a 
critical  process  for  the  plant,  70; 
duration  of,  128;  ecology  of,  69; 
and  weather,  70,  129 
Polyembryony,  149 
Polystichism  in  inflorescence,  loi, 

103,  no 
Polytoca,  8 

Popcorn:  endosperm  of ,  159,  162; 
general  references,  158,  159,  165, 


INDEX 


245 


167;  starch  and  protein  in,  159, 

161;  uses  of,  193 
Popping  of  corn,  161,  162 
Prescott,  reference  to  work  of,  215 
Primary  root  of  seedling,  60 
Proctor,  poem  by,  224,  225 
Prophyllum,  59 
Prop  roots,  64 
Protandry,  130 
Proteins:     in   a   balanced   ration, 

187;     in    corneous    endosperm, 

158;  formation  of,  54 
Protogyny,  130 
Prototype  of  maize,  31 
Pubescence,  nature  of,  53 
"Pufifed"  cereals,  162 
Puritans'  use  of  maize,  217 

Receptivity  of  stigma,  1 23 

Red  ears  of  corn,  219 

Remedies  for  attack:  of  fungi,  80; 

of  insects,  74 
Reserve  materials  in  endosperm, 

156-62 
Reversion,  24.  26 
Ridging  in  cultivation,  92 
Roasting  ears,  192,  212 
Rolling  of  leaf  blades,  52,  53 
Roman  corn,  5 

Root  cap:  origin  of,  148;  structure 
and  function  of,  60 

Root:  hairs,  61,  62;  pressure,  64; 
sheath.  See  Coleorhiza;  struc- 
ture of,  60-63;  system,  extent 
of,  60;  worms,  72 

Rows:  in  the  field,  distance  apart, 
87;  of  grains  on  the  ear,  103, 
104,  112,  113 

Rudiments  of:  branches,  56; 
cotyledon,  148,  149;  flower  in 
pistillate  spikelet,  117;  lodicules, 
117;  pistil,  116;  stamens,  117; 
various  organs,  26 

Rusts,  76 


Sacred  architecture,  maize  in,  215 

"Sacred"  corn  of  the  Navajos, 
156,  163 

Sahagun,  reference  to  work  of,  197 

Scandinavian  records  of  "corn"  in 
America,  11 

Schoolcraft,  reference  to  work  of, 
207 

Sclerachne,  8 

Scoring  of  corn,  141-44 

Scutellum,  ^3 

Secondary:  ears,  58;  roots  of 
seedlings,  35 

Secretion  by  roots,  64 

Sedg6s  distinguished  from  grasses, 
7 

Seedbed,  81,  82 

Seed:  care  of,  83;  coat,  31;  dry- 
ing of,  83;  grading,  84;  from 
Indian  mounds,  34;  parts  of,  32, 
$;};  selection  of,  83;  testing  of, 
83,  84;  viability  of,  33,  34 

Selection  in  breeding,  182 

Self-pollination:  effects  of,  130, 
131;  extent  of,  131;  methods  of 
avoiding,  183,  184 

Sexual:  differentiation  in  spike- 
lets,  119,  120;  origin  of  the 
endosperm,  139,  153,  154 

Sheath  of  the  leaf:  structure,  47, 
48;  as  a  support  for  the  meriste- 
matic  portion  of  the  internode, 
46 

Shocking  of  corn,  94-96 

"Shoe-peg"  grains,  166 

Show  corn,  141-44 

Shredder,  96 

Shrinkage  of  ripening  grain,  159 

Sicilian  corn,  5 

Silica  in  epidermis  of  stem,  41 

Silk:  medicinal  value  of,  195; 
origin,  123;  receptivity,  123; 
stigmatic  hairs,  123,  124;  struc- 
ture of,  123,  124.     See  Style 

Silos  and  ensilage,  98,  187 


246 


THE  STORY  OF  THE  MAIZE  PLANT 


Smut:  nature  of  the  disease,  78- 
80;  poisonous  effects  of,  79;  pre- 
vention of,  80 

"Smut  nose"  corn,  152 

Soft  corn,  142,  157-59 

Soft  endosperm,  histology  of,  157 

Soil  water,  88,  89 

Sorosis,  technical  term  for  ear  of 
corn,  140 

South  America,  maize  in,  15 

Specific  name  of  maize,  5 

Sperms,  formed  in  pollen  grain,  134 

Spikelets:  flowers  in,  7;  of 
grasses,  114;   of  maize,  115-20 

Spur  roots,  64 

Stamen:  development  of,  121; 
opening  of  anther,  121,  122; 
rudimentary,  125,  126 

Staminate:  inflorescence,  100- 
103;  spikelet,  115,  116 

Starch:  preparation  of,  190;  uses 
of,  190 

Starch  grains:  in  corneous  endo- 
sperm, 156,  157;  in  sweet  corn, 
159;  variation  in,  157 

Stem:  food  value  of,  186,  187,  194; 
structure  of,  140-46;  uses  of, 
194,  19s 

Sterile  plants,  104 

Stigma.    See  Silk  and  Style 

Stomata:  of  leaf,  49;  of  stem,  41 

Striped  leaves,  5 1 

Sturtevant,  reference  to  work  of, 
200 

Stylar  canal,  118,  120,  123 

Style:  origin  of,  120,  123,  124; 
structure  of,  123,  124.     See  Silk 

Suckers:  cultivation  and,  59; 
heredity  and,  59;  inflorescence 
of,  107-9;  mentioned,  39;  struc- 
ture of,  41 

Sugars  from  maize,  190,  193 

Suspensor  of  embryo,  148 

Sweet  corn:  ear- worm  in,  73; 
enzymes  in,   159,   160;    general 


reference,  142,  158,  167;  starch 
grains  in,  160;   uses  of,  192 

Synonymy  of  Zea  Mays  L.,  5,  6 

Syrup  from  corn,  191 

Tamales,  210 

Tassel:  structure  of,  100-103; 
types  of,  101-3 

Taylor,  quotation  from  poem  of, 
222 

Teosinte:  distribution  of,  9;  hy- 
brids with  maize,  24-26;  in- 
florescence of,  10;  uses  of,  9; 
as  wild  maize,  27 

Terracing,  208 

Testa,  32 

Tillage:  aims  of,  88-90;  methods 
of,  90-92 

Tillers.     See  Suckers 

Toltec  tradition,  202 

Topping  of  corn,  97 

Tortillas,  210 

Transpiration,  54,  63 

Tricarpellary  nature  of  pistil,  125 

Tripsaceae :  American  genera  of,  8; 
characteristics  of,  7,  8;  oriental 
genera  of,  8;  subdivisions  of,  8; 
synonym  for  Maydeae,  7 

Tripsacum:  distribution  of,  9;  in- 
florescence of,  9;  relation  of,  to 
maize,  9 

Turkish  corn,  5 

Turkish  wheat,  5 

Two-flowered  Distillate  spikelets, 
119 

Variation:  in  the  ear,  104-7,  142, 
143;  in  maize,  24;  in  the  tassel, 
1 01-3 

Varieties:  known  to  the  Indian, 
171, 172,  206;  nomenclature  of ,  6 

Vascular  bundles:  anastomosing 
of,  42;  of  leaf,  48,  50;  of  stem, 
42-44;  structure  of,  42,  43 

Vega,  de  la,  reference  to  work  of, 
197 


INDEX 


247 


Veins  of  the  leaf,  48,  50 
Vestigial   organs:    general    occur- 
rence, 26;  and  reversion,  26 
Viability  of  the  seed,  33,  84 
Vitamines  in  yellow  corn,  158 

Walker,  reference  to  work  of,  125 

Watson,  reference  to  work  of,  28 

"Waxy"  corn,  19,  156 

Weeds:  as  an  ecological  factor,  70; 
eradication  of,  88.  90 

Weevil,  74 

WTieat,  nutritive  value  of,  as  com- 
pared with  maize,  187,  196 

Whittier,  reference  to  poem  by,  223 

Wild  maize,  12,  27 

Wilt  diseases,  77 

Wind:  as  an  agent  of  pollination, 
127;  drying  effects  of,  68; 
mechanical  damage  done  by,  69 


Wire  worms,  71 

Wissler,  reference  to  work  of,  13 
Wolfe,  reference  to  work  of,  171 
Worsdell,  reference  to  work  of,  38 

Xenia:  definition  of,  171;  and 
double  fecundation,  173;  expla- 
nation of,  171-73;  first  men- 
tioned in  the  literature,  172; 
occurrence  of,  171;  in  other 
plants  than  maize,  171;  prin- 
ciples of,  173 

Yellow  corn,  vitamines  in,  158 
Yoking  of  pairs  of  spikelets,  1 1 2 
Yucatan,  probable  origin  of  maize 
in,  199,  200 

Zea,  derivation  of,  5 

Zea  Mays  L.,  origin  of  the  name,  5 

Zem,  a  protein  of  maize,  187 


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